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tree</a></li><li><a href="/en-US/docs/Glossary/Accessible_description">Accessible description</a></li><li><a href="/en-US/docs/Glossary/Accessible_name">Accessible name</a></li><li><a href="/en-US/docs/Glossary/Adobe_Flash">Adobe Flash</a></li><li><a href="/en-US/docs/Glossary/Advance_measure">Advance measure</a></li><li><a href="/en-US/docs/Glossary/AJAX">Ajax</a></li><li><a href="/en-US/docs/Glossary/Algorithm">Algorithm</a></li><li><a href="/en-US/docs/Glossary/Alignment_Container">Alignment container</a></li><li><a href="/en-US/docs/Glossary/Alignment_Subject">Alignment subject</a></li><li><a href="/en-US/docs/Glossary/Alpha">Alpha (alpha channel)</a></li><li><a href="/en-US/docs/Glossary/ALPN">ALPN</a></li><li><a href="/en-US/docs/Glossary/API">API</a></li><li><a href="/en-US/docs/Glossary/Apple_Safari">Apple Safari</a></li><li><a href="/en-US/docs/Glossary/Application_context">Application context</a></li><li><a href="/en-US/docs/Glossary/Argument">Argument</a></li><li><a href="/en-US/docs/Glossary/ARIA">ARIA</a></li><li><a href="/en-US/docs/Glossary/ARPA">ARPA</a></li><li><a href="/en-US/docs/Glossary/Arpanet">ARPANET</a></li><li><a href="/en-US/docs/Glossary/Array">Array</a></li><li><a href="/en-US/docs/Glossary/ASCII">ASCII</a></li><li><a href="/en-US/docs/Glossary/Aspect_ratio">Aspect ratio</a></li><li><a href="/en-US/docs/Glossary/Asynchronous">Asynchronous</a></li><li><a href="/en-US/docs/Glossary/ATAG">ATAG</a></li><li><a href="/en-US/docs/Glossary/Attribute">Attribute</a></li><li><a href="/en-US/docs/Glossary/Authentication">Authentication</a></li><li><a href="/en-US/docs/Glossary/Authenticator">Authenticator</a></li><li><a href="/en-US/docs/Glossary/Bandwidth">Bandwidth</a></li><li><a href="/en-US/docs/Glossary/Base64">Base64</a></li><li><a href="/en-US/docs/Glossary/Baseline">Baseline</a></li><li><a href="/en-US/docs/Glossary/Beacon">Beacon</a></li><li><a href="/en-US/docs/Glossary/Bezier_curve">Bézier curve</a></li><li><a href="/en-US/docs/Glossary/bfcache">bfcache</a></li><li><a href="/en-US/docs/Glossary/BiDi">BiDi</a></li><li><a href="/en-US/docs/Glossary/BigInt">BigInt</a></li><li><a href="/en-US/docs/Glossary/Binding">Binding</a></li><li><a href="/en-US/docs/Glossary/Bitwise_flags">Bitwise flags</a></li><li><a href="/en-US/docs/Glossary/Blink">Blink</a></li><li><a href="/en-US/docs/Glossary/blink_element">blink element (<blink> tag)</a></li><li><a href="/en-US/docs/Glossary/Block">Block</a></li><li><a href="/en-US/docs/Glossary/Block_cipher_mode_of_operation">Block cipher mode of operation</a></li><li><a href="/en-US/docs/Glossary/Block-level_content">Block-level content</a></li><li><a href="/en-US/docs/Glossary/Boolean">Boolean</a></li><li><a href="/en-US/docs/Glossary/Bounding_box">Bounding Box</a></li><li><a href="/en-US/docs/Glossary/Breadcrumb">Breadcrumb</a></li><li><a href="/en-US/docs/Glossary/Brotli_compression">Brotli compression</a></li><li><a href="/en-US/docs/Glossary/Browser">Browser</a></li><li><a href="/en-US/docs/Glossary/Browsing_context">Browsing context</a></li><li><a href="/en-US/docs/Glossary/Buffer">Buffer</a></li><li><a href="/en-US/docs/Glossary/Cache">Cache</a></li><li><a href="/en-US/docs/Glossary/Cacheable">Cacheable</a></li><li><a href="/en-US/docs/Glossary/CalDAV">CalDAV</a></li><li><a href="/en-US/docs/Glossary/Call_stack">Call stack</a></li><li><a href="/en-US/docs/Glossary/Callback_function">Callback function</a></li><li><a href="/en-US/docs/Glossary/Camel_case">Camel case</a></li><li><a href="/en-US/docs/Glossary/Canonical_order">Canonical order</a></li><li><a href="/en-US/docs/Glossary/Canvas">Canvas</a></li><li><a href="/en-US/docs/Glossary/Card_sorting">Card sorting</a></li><li><a href="/en-US/docs/Glossary/CardDAV">CardDAV</a></li><li><a href="/en-US/docs/Glossary/Caret">Caret</a></li><li><a href="/en-US/docs/Glossary/CDN">CDN</a></li><li><a href="/en-US/docs/Glossary/Certificate_authority">Certificate authority</a></li><li><a href="/en-US/docs/Glossary/Certified">Certified</a></li><li><a href="/en-US/docs/Glossary/Challenge">Challenge-response authentication</a></li><li><a href="/en-US/docs/Glossary/Character">Character</a></li><li><a href="/en-US/docs/Glossary/Character_encoding">Character encoding</a></li><li><a href="/en-US/docs/Glossary/Character_reference">Character reference</a></li><li><a href="/en-US/docs/Glossary/Character_set">Character set</a></li><li><a href="/en-US/docs/Glossary/Chrome">Chrome</a></li><li><a href="/en-US/docs/Glossary/CIA">CIA</a></li><li><a href="/en-US/docs/Glossary/Cipher">Cipher</a></li><li><a href="/en-US/docs/Glossary/Cipher_suite">Cipher suite</a></li><li><a href="/en-US/docs/Glossary/Ciphertext">Ciphertext</a></li><li><a href="/en-US/docs/Glossary/Class">Class</a></li><li><a href="/en-US/docs/Glossary/Clickjacking">Clickjacking</a></li><li><a href="/en-US/docs/Glossary/Closure">Closure</a></li><li><a href="/en-US/docs/Glossary/Cloud">Cloud</a></li><li><a href="/en-US/docs/Glossary/Cloud_computing">Cloud computing</a></li><li><a href="/en-US/docs/Glossary/CMS">CMS</a></li><li><a href="/en-US/docs/Glossary/Code_point">Code point</a></li><li><a href="/en-US/docs/Glossary/Code_splitting">Code splitting</a></li><li><a href="/en-US/docs/Glossary/Code_unit">Code unit</a></li><li><a href="/en-US/docs/Glossary/Codec">Codec</a></li><li><a href="/en-US/docs/Glossary/Color_space">Color space</a></li><li><a href="/en-US/docs/Glossary/Color_wheel">Color wheel</a></li><li><a href="/en-US/docs/Glossary/Compile">Compile</a></li><li><a href="/en-US/docs/Glossary/Compile_time">Compile time</a></li><li><a href="/en-US/docs/Glossary/Composite_operation">Composite operation</a></li><li><a href="/en-US/docs/Glossary/Computer_Programming">Computer Programming</a></li><li><a href="/en-US/docs/Glossary/Conditional">Conditional</a></li><li><a href="/en-US/docs/Glossary/Constant">Constant</a></li><li><a href="/en-US/docs/Glossary/Constructor">Constructor</a></li><li><a href="/en-US/docs/Glossary/Content_header">Content header</a></li><li><a href="/en-US/docs/Glossary/Continuous_Media">Continuous Media</a></li><li><a href="/en-US/docs/Glossary/Control_flow">Control flow</a></li><li><a href="/en-US/docs/Glossary/Cookie">Cookie</a></li><li><a href="/en-US/docs/Glossary/Copyleft">Copyleft</a></li><li><a href="/en-US/docs/Glossary/CORS">CORS</a></li><li><a href="/en-US/docs/Glossary/CORS-safelisted_request_header">CORS-safelisted request header</a></li><li><a href="/en-US/docs/Glossary/CORS-safelisted_response_header">CORS-safelisted response header</a></li><li><a href="/en-US/docs/Glossary/Crawler">Crawler</a></li><li><a href="/en-US/docs/Glossary/Credential">Credential</a></li><li><a href="/en-US/docs/Glossary/CRLF">CRLF</a></li><li><a href="/en-US/docs/Glossary/Cross_Axis">Cross Axis</a></li><li><a href="/en-US/docs/Glossary/Cross-site_scripting">Cross-site scripting (XSS)</a></li><li><a href="/en-US/docs/Glossary/CRUD">CRUD</a></li><li><a href="/en-US/docs/Glossary/Cryptanalysis">Cryptanalysis</a></li><li><a href="/en-US/docs/Glossary/Cryptographic_hash_function">Cryptographic hash function</a></li><li><a href="/en-US/docs/Glossary/Cryptography">Cryptography</a></li><li><a href="/en-US/docs/Glossary/CSP">CSP</a></li><li><a href="/en-US/docs/Glossary/CSRF">CSRF</a></li><li><a href="/en-US/docs/Glossary/CSS">CSS</a></li><li><a href="/en-US/docs/Glossary/CSSOM">CSS Object Model (CSSOM)</a></li><li><a href="/en-US/docs/Glossary/CSS_pixel">CSS pixel</a></li><li><a href="/en-US/docs/Glossary/CSS_preprocessor">CSS preprocessor</a></li><li><a href="/en-US/docs/Glossary/CLS">Cumulative Layout Shift (CLS)</a></li><li><a href="/en-US/docs/Glossary/Data_structure">Data structure</a></li><li><a href="/en-US/docs/Glossary/Database">Database</a></li><li><a href="/en-US/docs/Glossary/Debounce">Debounce</a></li><li><a href="/en-US/docs/Glossary/Decryption">Decryption</a></li><li><a href="/en-US/docs/Glossary/Deep_copy">Deep copy</a></li><li><a href="/en-US/docs/Glossary/Delta">Delta</a></li><li><a href="/en-US/docs/Glossary/Denial_of_Service">Denial of Service</a></li><li><a href="/en-US/docs/Glossary/Deno">Deno</a></li><li><a href="/en-US/docs/Glossary/CSS_Descriptor">Descriptor (CSS)</a></li><li><a href="/en-US/docs/Glossary/Deserialization">Deserialization</a></li><li><a href="/en-US/docs/Glossary/Developer_Tools">Developer Tools</a></li><li><a href="/en-US/docs/Glossary/Digest">Digest</a></li><li><a href="/en-US/docs/Glossary/Digital_certificate">Digital certificate</a></li><li><a href="/en-US/docs/Glossary/Digital_signature">Digital signature</a></li><li><a href="/en-US/docs/Glossary/Distributed_Denial_of_Service">Distributed Denial of Service</a></li><li><a href="/en-US/docs/Glossary/DMZ">DMZ</a></li><li><a href="/en-US/docs/Glossary/DNS">DNS</a></li><li><a href="/en-US/docs/Glossary/Doctype">Doctype</a></li><li><a href="/en-US/docs/Glossary/Document_directive">Document directive</a></li><li><a href="/en-US/docs/Glossary/Document_environment">Document environment</a></li><li><a href="/en-US/docs/Glossary/DOM">DOM (Document Object Model)</a></li><li><a href="/en-US/docs/Glossary/Domain">Domain</a></li><li><a href="/en-US/docs/Glossary/Domain_name">Domain name</a></li><li><a href="/en-US/docs/Glossary/Domain_sharding">Domain sharding</a></li><li><a href="/en-US/docs/Glossary/Dominator">Dominator</a></li><li><a href="/en-US/docs/Glossary/DOS_attack">DoS attack</a></li><li><a href="/en-US/docs/Glossary/DSL">DSL</a></li><li><a href="/en-US/docs/Glossary/DTLS">DTLS (Datagram Transport Layer Security)</a></li><li><a href="/en-US/docs/Glossary/DTMF">DTMF (Dual-Tone Multi-Frequency signaling)</a></li><li><a href="/en-US/docs/Glossary/Dynamic_typing">Dynamic typing</a></li><li><a href="/en-US/docs/Glossary/ECMA">ECMA</a></li><li><a href="/en-US/docs/Glossary/ECMAScript">ECMAScript</a></li><li><a href="/en-US/docs/Glossary/Effective_connection_type">Effective connection type</a></li><li><a href="/en-US/docs/Glossary/Element">Element</a></li><li><a href="/en-US/docs/Glossary/Encapsulation">Encapsulation</a></li><li><a href="/en-US/docs/Glossary/Encryption">Encryption</a></li><li><a href="/en-US/docs/Glossary/Endianness">Endianness</a></li><li><a href="/en-US/docs/Glossary/Engine">Engine</a></li><li><a href="/en-US/docs/Glossary/Entity">Entity</a></li><li><a href="/en-US/docs/Glossary/Entity_header">Entity header</a></li><li><a href="/en-US/docs/Glossary/Enumerated">Enumerated</a></li><li><a href="/en-US/docs/Glossary/eTLD">eTLD</a></li><li><a href="/en-US/docs/Glossary/Event">Event</a></li><li><a href="/en-US/docs/Glossary/Exception">Exception</a></li><li><a href="/en-US/docs/Glossary/EXIF">EXIF</a></li><li><a href="/en-US/docs/Glossary/Expando">Expando</a></li><li><a href="/en-US/docs/Glossary/Fallback_Alignment">Fallback alignment</a></li><li><a href="/en-US/docs/Glossary/Falsy">Falsy</a></li><li><a href="/en-US/docs/Glossary/Favicon">Favicon</a></li><li><a href="/en-US/docs/Glossary/Federated_identity">Federated identity</a></li><li><a href="/en-US/docs/Glossary/Fetch_directive">Fetch directive</a></li><li><a href="/en-US/docs/Glossary/Fetch_metadata_request_header">Fetch metadata request header</a></li><li><a href="/en-US/docs/Glossary/Fingerprinting">Fingerprinting</a></li><li><a href="/en-US/docs/Glossary/Firefox_OS">Firefox OS</a></li><li><a href="/en-US/docs/Glossary/Firewall">Firewall</a></li><li><a href="/en-US/docs/Glossary/First_contentful_paint">First Contentful Paint (FCP)</a></li><li><a href="/en-US/docs/Glossary/First_CPU_idle">First CPU idle</a></li><li><a href="/en-US/docs/Glossary/First_input_delay">First Input Delay (FID)</a><abbr class="icon icon-deprecated" 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Not for use in new websites."> <span class="visually-hidden">Deprecated</span> </abbr></li><li><a href="/en-US/docs/Glossary/First_meaningful_paint">First Meaningful Paint (FMP)</a></li><li><a href="/en-US/docs/Glossary/First_paint">First Paint (FP)</a></li><li><a href="/en-US/docs/Glossary/First-class_Function">First-class Function</a></li><li><a href="/en-US/docs/Glossary/Flex">Flex</a></li><li><a href="/en-US/docs/Glossary/Flex_Container">Flex Container</a></li><li><a href="/en-US/docs/Glossary/Flex_Item">Flex Item</a></li><li><a href="/en-US/docs/Glossary/Flexbox">Flexbox</a></li><li><a href="/en-US/docs/Glossary/Flow_relative_values">Flow relative values</a></li><li><a href="/en-US/docs/Glossary/Forbidden_header_name">Forbidden header name</a></li><li><a href="/en-US/docs/Glossary/Forbidden_response_header_name">Forbidden response header name</a></li><li><a href="/en-US/docs/Glossary/Fork">Fork</a></li><li><a href="/en-US/docs/Glossary/Fragmentainer">Fragmentainer</a></li><li><a href="/en-US/docs/Glossary/FPS">Frame rate (FPS)</a></li><li><a href="/en-US/docs/Glossary/FTP">FTP</a></li><li><a href="/en-US/docs/Glossary/FTU">FTU</a></li><li><em><a href="/en-US/docs/Glossary/Function" aria-current="page">Function</a></em></li><li><a href="/en-US/docs/Glossary/Fuzzing">Fuzz testing</a></li><li><a href="/en-US/docs/Glossary/Gamut">Gamut</a></li><li><a href="/en-US/docs/Glossary/Garbage_collection">Garbage collection</a></li><li><a href="/en-US/docs/Glossary/Gecko">Gecko</a></li><li><a href="/en-US/docs/Glossary/General_header">General header</a></li><li><a href="/en-US/docs/Glossary/GIF">GIF</a></li><li><a href="/en-US/docs/Glossary/Git">Git</a></li><li><a href="/en-US/docs/Glossary/Global_object">Global object</a></li><li><a href="/en-US/docs/Glossary/Global_scope">Global scope</a></li><li><a href="/en-US/docs/Glossary/Global_variable">Global variable</a></li><li><a href="/en-US/docs/Glossary/Glyph">Glyph</a></li><li><a href="/en-US/docs/Glossary/Google_Chrome">Google Chrome</a></li><li><a href="/en-US/docs/Glossary/GPL">GPL</a></li><li><a href="/en-US/docs/Glossary/GPU">GPU</a></li><li><a href="/en-US/docs/Glossary/Graceful_degradation">Graceful degradation</a></li><li><a href="/en-US/docs/Glossary/Grid">Grid</a></li><li><a href="/en-US/docs/Glossary/Grid_Areas">Grid Areas</a></li><li><a href="/en-US/docs/Glossary/Grid_Axis">Grid Axis</a></li><li><a href="/en-US/docs/Glossary/Grid_Cell">Grid Cell</a></li><li><a href="/en-US/docs/Glossary/Grid_Column">Grid Column</a></li><li><a href="/en-US/docs/Glossary/Grid_Container">Grid container</a></li><li><a href="/en-US/docs/Glossary/Grid_Lines">Grid Lines</a></li><li><a href="/en-US/docs/Glossary/Grid_Row">Grid Row</a></li><li><a href="/en-US/docs/Glossary/Grid_Tracks">Grid Tracks</a></li><li><a href="/en-US/docs/Glossary/Gutters">Gutters</a></li><li><a href="/en-US/docs/Glossary/gzip_compression">gzip compression</a></li><li><a href="/en-US/docs/Glossary/Hash">Hash</a></li><li><a href="/en-US/docs/Glossary/Head">Head</a></li><li><a href="/en-US/docs/Glossary/High-level_programming_language">High-level programming language</a></li><li><a href="/en-US/docs/Glossary/HMAC">HMAC</a></li><li><a href="/en-US/docs/Glossary/Hoisting">Hoisting</a></li><li><a href="/en-US/docs/Glossary/Host">Host</a></li><li><a href="/en-US/docs/Glossary/Hotlink">Hotlink</a></li><li><a href="/en-US/docs/Glossary/Houdini">Houdini</a></li><li><a href="/en-US/docs/Glossary/HPKP">HPKP</a></li><li><a href="/en-US/docs/Glossary/HSTS">HSTS</a></li><li><a href="/en-US/docs/Glossary/HTML">HTML</a></li><li><a href="/en-US/docs/Glossary/html_color_codes">HTML color codes</a></li><li><a href="/en-US/docs/Glossary/HTML5">HTML5</a></li><li><a href="/en-US/docs/Glossary/HTTP">HTTP</a></li><li><a href="/en-US/docs/Glossary/HTTP_Content">HTTP Content</a></li><li><a href="/en-US/docs/Glossary/HTTP_header">HTTP header</a></li><li><a href="/en-US/docs/Glossary/HTTP_2">HTTP/2</a></li><li><a href="/en-US/docs/Glossary/HTTP_3">HTTP/3</a></li><li><a href="/en-US/docs/Glossary/HTTPS">HTTPS</a></li><li><a href="/en-US/docs/Glossary/HTTPS_RR">HTTPS RR</a></li><li><a href="/en-US/docs/Glossary/Hyperlink">Hyperlink</a></li><li><a href="/en-US/docs/Glossary/Hypertext">Hypertext</a></li><li><a href="/en-US/docs/Glossary/IANA">IANA</a></li><li><a href="/en-US/docs/Glossary/ICANN">ICANN</a></li><li><a href="/en-US/docs/Glossary/ICE">ICE</a></li><li><a href="/en-US/docs/Glossary/IDE">IDE</a></li><li><a href="/en-US/docs/Glossary/Idempotent">Idempotent</a></li><li><a href="/en-US/docs/Glossary/Identifier">Identifier</a></li><li><a href="/en-US/docs/Glossary/Identity_provider">Identity provider (IdP)</a></li><li><a href="/en-US/docs/Glossary/IDL">IDL</a></li><li><a href="/en-US/docs/Glossary/IETF">IETF</a></li><li><a href="/en-US/docs/Glossary/IIFE">IIFE</a></li><li><a href="/en-US/docs/Glossary/IMAP">IMAP</a></li><li><a href="/en-US/docs/Glossary/Immutable">Immutable</a></li><li><a href="/en-US/docs/Glossary/IndexedDB">IndexedDB</a></li><li><a href="/en-US/docs/Glossary/Information_architecture">Information architecture</a></li><li><a href="/en-US/docs/Glossary/Inheritance">Inheritance</a></li><li><a href="/en-US/docs/Glossary/Ink_overflow">Ink overflow</a></li><li><a href="/en-US/docs/Glossary/Inline-level_content">Inline-level content</a></li><li><a href="/en-US/docs/Glossary/Input_method_editor">Input method editor</a></li><li><a href="/en-US/docs/Glossary/Inset_properties">Inset properties</a></li><li><a href="/en-US/docs/Glossary/Instance">Instance</a></li><li><a href="/en-US/docs/Glossary/Interaction_to_next_paint">Interaction to Next Paint (INP)</a></li><li><a href="/en-US/docs/Glossary/Internationalization">Internationalization (i18n)</a></li><li><a href="/en-US/docs/Glossary/Internet">Internet</a></li><li><a href="/en-US/docs/Glossary/Interpolation">Interpolation</a></li><li><a href="/en-US/docs/Glossary/Intrinsic_Size">Intrinsic size</a></li><li><a href="/en-US/docs/Glossary/IP_Address">IP Address</a></li><li><a href="/en-US/docs/Glossary/IPv4">IPv4</a></li><li><a href="/en-US/docs/Glossary/IPv6">IPv6</a></li><li><a href="/en-US/docs/Glossary/IRC">IRC</a></li><li><a href="/en-US/docs/Glossary/ISO">ISO</a></li><li><a href="/en-US/docs/Glossary/ISP">ISP</a></li><li><a href="/en-US/docs/Glossary/ITU">ITU</a></li><li><a href="/en-US/docs/Glossary/Jank">Jank</a></li><li><a href="/en-US/docs/Glossary/Java">Java</a></li><li><a href="/en-US/docs/Glossary/JavaScript">JavaScript</a></li><li><a href="/en-US/docs/Glossary/Jitter">Jitter</a></li><li><a href="/en-US/docs/Glossary/JPEG">JPEG</a></li><li><a href="/en-US/docs/Glossary/JSON">JSON</a></li><li><a href="/en-US/docs/Glossary/JSON_type_representation">JSON type representation</a></li><li><a href="/en-US/docs/Glossary/Kebab_case">Kebab case</a></li><li><a href="/en-US/docs/Glossary/Key">Key</a></li><li><a href="/en-US/docs/Glossary/Keyword">Keyword</a></li><li><a href="/en-US/docs/Glossary/Largest_contentful_paint">Largest Contentful Paint (LCP)</a></li><li><a href="/en-US/docs/Glossary/Latency">Latency</a></li><li><a href="/en-US/docs/Glossary/Layout_viewport">Layout viewport</a></li><li><a href="/en-US/docs/Glossary/Lazy_load">Lazy load</a></li><li><a href="/en-US/docs/Glossary/LGPL">LGPL</a></li><li><a href="/en-US/docs/Glossary/Ligature">Ligature</a></li><li><a href="/en-US/docs/Glossary/Literal">Literal</a></li><li><a href="/en-US/docs/Glossary/Local_scope">Local scope</a></li><li><a href="/en-US/docs/Glossary/Local_variable">Local variable</a></li><li><a href="/en-US/docs/Glossary/Locale">Locale</a></li><li><a href="/en-US/docs/Glossary/Localization">Localization</a></li><li><a href="/en-US/docs/Glossary/Logical_properties">Logical properties</a></li><li><a href="/en-US/docs/Glossary/Long_task">Long task</a></li><li><a href="/en-US/docs/Glossary/Loop">Loop</a></li><li><a href="/en-US/docs/Glossary/Lossless_compression">Lossless compression</a></li><li><a href="/en-US/docs/Glossary/Lossy_compression">Lossy compression</a></li><li><a href="/en-US/docs/Glossary/LTR">LTR (Left To Right)</a></li><li><a href="/en-US/docs/Glossary/Main_Axis">Main Axis</a></li><li><a href="/en-US/docs/Glossary/Main_thread">Main thread</a></li><li><a href="/en-US/docs/Glossary/Markup">Markup</a></li><li><a href="/en-US/docs/Glossary/MathML">MathML</a></li><li><a href="/en-US/docs/Glossary/Media">Media</a></li><li><a href="/en-US/docs/Glossary/Media_query">Media query</a></li><li><a href="/en-US/docs/Glossary/Metadata">Metadata</a></li><li><a href="/en-US/docs/Glossary/Method">Method</a></li><li><a href="/en-US/docs/Glossary/Microsoft_Edge">Microsoft Edge</a></li><li><a href="/en-US/docs/Glossary/Microsoft_Internet_Explorer">Microsoft Internet Explorer</a></li><li><a href="/en-US/docs/Glossary/Middleware">Middleware</a></li><li><a href="/en-US/docs/Glossary/MIME">MIME</a></li><li><a href="/en-US/docs/Glossary/MIME_type">MIME type</a></li><li><a href="/en-US/docs/Glossary/Minification">Minification</a></li><li><a href="/en-US/docs/Glossary/MitM">MitM</a></li><li><a href="/en-US/docs/Glossary/Mixin">Mixin</a></li><li><a href="/en-US/docs/Glossary/Mobile_First">Mobile First</a></li><li><a href="/en-US/docs/Glossary/Modem">Modem</a></li><li><a href="/en-US/docs/Glossary/Modularity">Modularity</a></li><li><a href="/en-US/docs/Glossary/Mozilla_Firefox">Mozilla Firefox</a></li><li><a href="/en-US/docs/Glossary/Mutable">Mutable</a></li><li><a href="/en-US/docs/Glossary/MVC">MVC</a></li><li><a href="/en-US/docs/Glossary/Namespace">Namespace</a></li><li><a href="/en-US/docs/Glossary/NaN">NaN</a></li><li><a href="/en-US/docs/Glossary/NAT">NAT</a></li><li><a href="/en-US/docs/Glossary/Native">Native</a></li><li><a href="/en-US/docs/Glossary/Navigation_directive">Navigation directive</a></li><li><a href="/en-US/docs/Glossary/Netscape_Navigator">Netscape Navigator</a></li><li><a href="/en-US/docs/Glossary/Network_throttling">Network throttling</a></li><li><a href="/en-US/docs/Glossary/NNTP">NNTP</a></li><li><a href="/en-US/docs/Glossary/Node">Node</a></li><li><a href="/en-US/docs/Glossary/Node.js">Node.js</a></li><li><a href="/en-US/docs/Glossary/Non-normative">Non-normative</a></li><li><a href="/en-US/docs/Glossary/Normative">Normative</a></li><li><a href="/en-US/docs/Glossary/Null">Null</a></li><li><a href="/en-US/docs/Glossary/Nullish">Nullish value</a></li><li><a href="/en-US/docs/Glossary/Number">Number</a></li><li><a href="/en-US/docs/Glossary/Object">Object</a></li><li><a href="/en-US/docs/Glossary/Object_reference">Object reference</a></li><li><a href="/en-US/docs/Glossary/OOP">OOP</a></li><li><a href="/en-US/docs/Glossary/OpenGL">OpenGL</a></li><li><a href="/en-US/docs/Glossary/OpenSSL">OpenSSL</a></li><li><a href="/en-US/docs/Glossary/Opera_Browser">Opera Browser</a></li><li><a href="/en-US/docs/Glossary/Operand">Operand</a></li><li><a href="/en-US/docs/Glossary/Operator">Operator</a></li><li><a href="/en-US/docs/Glossary/Origin">Origin</a></li><li><a href="/en-US/docs/Glossary/OTA">OTA</a></li><li><a href="/en-US/docs/Glossary/OWASP">OWASP</a></li><li><a href="/en-US/docs/Glossary/P2P">P2P</a></li><li><a href="/en-US/docs/Glossary/PAC">PAC</a></li><li><a href="/en-US/docs/Glossary/Packet">Packet</a></li><li><a href="/en-US/docs/Glossary/Page_load_time">Page load time</a></li><li><a href="/en-US/docs/Glossary/Page_prediction">Page prediction</a></li><li><a href="/en-US/docs/Glossary/Parameter">Parameter</a></li><li><a href="/en-US/docs/Glossary/Parent_object">Parent object</a></li><li><a href="/en-US/docs/Glossary/Parse">Parse</a></li><li><a href="/en-US/docs/Glossary/Parser">Parser</a></li><li><a href="/en-US/docs/Glossary/Payload_body">Payload body</a></li><li><a href="/en-US/docs/Glossary/Payload_header">Payload header</a></li><li><a href="/en-US/docs/Glossary/PDF">PDF</a></li><li><a href="/en-US/docs/Glossary/Perceived_performance">Perceived performance</a></li><li><a href="/en-US/docs/Glossary/Percent-encoding">Percent-encoding</a></li><li><a href="/en-US/docs/Glossary/PHP">PHP</a></li><li><a href="/en-US/docs/Glossary/Physical_properties">Physical properties</a></li><li><a href="/en-US/docs/Glossary/Pixel">Pixel</a></li><li><a href="/en-US/docs/Glossary/Placeholder_names">Placeholder names</a></li><li><a href="/en-US/docs/Glossary/Plaintext">Plaintext</a></li><li><a href="/en-US/docs/Glossary/Plugin">Plugin</a></li><li><a href="/en-US/docs/Glossary/PNG">PNG</a></li><li><a href="/en-US/docs/Glossary/Polyfill">Polyfill</a></li><li><a href="/en-US/docs/Glossary/Polymorphism">Polymorphism</a></li><li><a href="/en-US/docs/Glossary/POP">POP3</a></li><li><a href="/en-US/docs/Glossary/Port">Port</a></li><li><a href="/en-US/docs/Glossary/Prefetch">Prefetch</a></li><li><a href="/en-US/docs/Glossary/Preflight_request">Preflight request</a></li><li><a href="/en-US/docs/Glossary/Prerender">Prerender</a></li><li><a href="/en-US/docs/Glossary/Presto">Presto</a></li><li><a href="/en-US/docs/Glossary/Primitive">Primitive</a></li><li><a href="/en-US/docs/Glossary/Privileged">Privileged</a></li><li><a href="/en-US/docs/Glossary/Privileged_code">Privileged code</a></li><li><a href="/en-US/docs/Glossary/Progressive_Enhancement">Progressive Enhancement</a></li><li><a href="/en-US/docs/Glossary/Progressive_web_apps">Progressive web apps</a></li><li><a href="/en-US/docs/Glossary/Promise">Promise</a></li><li><a href="/en-US/docs/Glossary/Property">Property</a></li><li><a href="/en-US/docs/Glossary/Protocol">Protocol</a></li><li><a href="/en-US/docs/Glossary/Prototype">Prototype</a></li><li><a href="/en-US/docs/Glossary/Prototype-based_programming">Prototype-based programming</a></li><li><a href="/en-US/docs/Glossary/Proxy_server">Proxy server</a></li><li><a href="/en-US/docs/Glossary/Pseudo-class">Pseudo-class</a></li><li><a href="/en-US/docs/Glossary/Pseudo-element">Pseudo-element</a></li><li><a href="/en-US/docs/Glossary/Pseudocode">Pseudocode</a></li><li><a href="/en-US/docs/Glossary/Public-key_cryptography">Public-key cryptography</a></li><li><a href="/en-US/docs/Glossary/Python">Python</a></li><li><a href="/en-US/docs/Glossary/Quality_values">Quality values</a></li><li><a href="/en-US/docs/Glossary/Quaternion">Quaternion</a></li><li><a href="/en-US/docs/Glossary/QUIC">QUIC</a></li><li><a href="/en-US/docs/Glossary/RAIL">RAIL</a></li><li><a href="/en-US/docs/Glossary/RNG">Random Number Generator</a></li><li><a href="/en-US/docs/Glossary/Raster_image">Raster image</a></li><li><a href="/en-US/docs/Glossary/Rate_limit">Rate limit</a></li><li><a href="/en-US/docs/Glossary/RDF">RDF</a></li><li><a href="/en-US/docs/Glossary/Real_User_Monitoring">Real User Monitoring (RUM)</a></li><li><a href="/en-US/docs/Glossary/Recursion">Recursion</a></li><li><a href="/en-US/docs/Glossary/Reflow">Reflow</a></li><li><a href="/en-US/docs/Glossary/Regular_expression">Regular expression</a></li><li><a href="/en-US/docs/Glossary/Relying_party">Relying party</a></li><li><a href="/en-US/docs/Glossary/Render_blocking">Render-blocking</a></li><li><a href="/en-US/docs/Glossary/Repaint">Repaint</a></li><li><a href="/en-US/docs/Glossary/Replay_attack">Replay attack</a></li><li><a href="/en-US/docs/Glossary/Repo">Repo</a></li><li><a href="/en-US/docs/Glossary/Reporting_directive">Reporting directive</a></li><li><a href="/en-US/docs/Glossary/Representation_header">Representation header</a></li><li><a href="/en-US/docs/Glossary/Request_header">Request header</a></li><li><a href="/en-US/docs/Glossary/Resource_Timing">Resource Timing</a></li><li><a href="/en-US/docs/Glossary/Response_header">Response header</a></li><li><a href="/en-US/docs/Glossary/Responsive_web_design">Responsive web design</a></li><li><a href="/en-US/docs/Glossary/REST">REST</a></li><li><a href="/en-US/docs/Glossary/RGB">RGB</a></li><li><a href="/en-US/docs/Glossary/RIL">RIL</a></li><li><a href="/en-US/docs/Glossary/Robots.txt">Robots.txt</a></li><li><a href="/en-US/docs/Glossary/Round_Trip_Time">Round Trip Time (RTT)</a></li><li><a href="/en-US/docs/Glossary/Router">Router</a></li><li><a href="/en-US/docs/Glossary/RSS">RSS</a></li><li><a href="/en-US/docs/Glossary/Rsync">Rsync</a></li><li><a href="/en-US/docs/Glossary/RTCP">RTCP (RTP Control Protocol)</a></li><li><a href="/en-US/docs/Glossary/RTF">RTF</a></li><li><a href="/en-US/docs/Glossary/RTL">RTL (Right to Left)</a></li><li><a href="/en-US/docs/Glossary/RTP">RTP (Real-time Transport Protocol) and SRTP (Secure RTP)</a></li><li><a href="/en-US/docs/Glossary/RTSP">RTSP: Real-time streaming protocol</a></li><li><a href="/en-US/docs/Glossary/Ruby">Ruby</a></li><li><a href="/en-US/docs/Glossary/Safe">Safe</a></li><li><a href="/en-US/docs/Glossary/Salt">Salt</a></li><li><a href="/en-US/docs/Glossary/Same-origin_policy">Same-origin policy</a></li><li><a href="/en-US/docs/Glossary/SCM">SCM</a></li><li><a href="/en-US/docs/Glossary/Scope">Scope</a></li><li><a href="/en-US/docs/Glossary/Screen_reader">Screen reader</a></li><li><a href="/en-US/docs/Glossary/Script-supporting_element">Script-supporting element</a></li><li><a href="/en-US/docs/Glossary/Scroll_boundary">Scroll boundary</a></li><li><a href="/en-US/docs/Glossary/Scroll_chaining">Scroll chaining</a></li><li><a href="/en-US/docs/Glossary/Scroll_container">Scroll container</a></li><li><a href="/en-US/docs/Glossary/Scroll_snap">Scroll snap</a></li><li><a href="/en-US/docs/Glossary/SCTP">SCTP</a></li><li><a href="/en-US/docs/Glossary/SDK">SDK (Software Development Kit)</a></li><li><a href="/en-US/docs/Glossary/SDP">SDP</a></li><li><a href="/en-US/docs/Glossary/Search_engine">Search engine</a></li><li><a href="/en-US/docs/Glossary/Secure_Context">Secure Context</a></li><li><a href="/en-US/docs/Glossary/SSL">Secure Sockets Layer (SSL)</a></li><li><a href="/en-US/docs/Glossary/CSS_Selector">Selector (CSS)</a></li><li><a href="/en-US/docs/Glossary/Self-Executing_Anonymous_Function">Self-Executing Anonymous Function</a></li><li><a href="/en-US/docs/Glossary/Semantics">Semantics</a></li><li><a href="/en-US/docs/Glossary/SEO">SEO</a></li><li><a href="/en-US/docs/Glossary/Serializable_object">Serializable object</a></li><li><a href="/en-US/docs/Glossary/Serialization">Serialization</a></li><li><a href="/en-US/docs/Glossary/Server">Server</a></li><li><a href="/en-US/docs/Glossary/Server_Timing">Server Timing</a></li><li><a href="/en-US/docs/Glossary/Session_Hijacking">Session Hijacking</a></li><li><a href="/en-US/docs/Glossary/SGML">SGML</a></li><li><a href="/en-US/docs/Glossary/Shadow_tree">Shadow tree</a></li><li><a href="/en-US/docs/Glossary/Shallow_copy">Shallow copy</a></li><li><a href="/en-US/docs/Glossary/Shim">Shim</a></li><li><a href="/en-US/docs/Glossary/Signature">Signature</a></li><li><a href="/en-US/docs/Glossary/SIMD">SIMD</a></li><li><a href="/en-US/docs/Glossary/SISD">SISD</a></li><li><a href="/en-US/docs/Glossary/Site">Site</a></li><li><a href="/en-US/docs/Glossary/Site_map">Site map</a></li><li><a href="/en-US/docs/Glossary/SLD">SLD</a></li><li><a href="/en-US/docs/Glossary/Sloppy_mode">Sloppy mode</a></li><li><a href="/en-US/docs/Glossary/Slug">Slug</a></li><li><a href="/en-US/docs/Glossary/Smoke_Test">Smoke Test</a></li><li><a href="/en-US/docs/Glossary/SMPTE">SMPTE (Society of Motion Picture and Television Engineers)</a></li><li><a href="/en-US/docs/Glossary/SMTP">SMTP</a></li><li><a href="/en-US/docs/Glossary/Snake_case">Snake case</a></li><li><a href="/en-US/docs/Glossary/Snap_positions">Snap positions</a></li><li><a href="/en-US/docs/Glossary/SOAP">SOAP</a></li><li><a href="/en-US/docs/Glossary/SPA">SPA (Single-page application)</a></li><li><a href="/en-US/docs/Glossary/Specification">Specification</a></li><li><a href="/en-US/docs/Glossary/Speculative_parsing">Speculative parsing</a></li><li><a href="/en-US/docs/Glossary/Speed_index">Speed index</a></li><li><a href="/en-US/docs/Glossary/SQL">SQL</a></li><li><a href="/en-US/docs/Glossary/SQL_Injection">SQL Injection</a></li><li><a href="/en-US/docs/Glossary/SRI">SRI</a></li><li><a href="/en-US/docs/Glossary/Stacking_context">Stacking context</a></li><li><a href="/en-US/docs/Glossary/State_machine">State machine</a></li><li><a href="/en-US/docs/Glossary/Statement">Statement</a></li><li><a href="/en-US/docs/Glossary/Static_method">Static method</a></li><li><a href="/en-US/docs/Glossary/SSG">Static site generator (SSG)</a></li><li><a href="/en-US/docs/Glossary/Static_typing">Static typing</a></li><li><a href="/en-US/docs/Glossary/Sticky_activation">Sticky activation</a></li><li><a href="/en-US/docs/Glossary/Strict_mode">Strict mode</a></li><li><a href="/en-US/docs/Glossary/String">String</a></li><li><a href="/en-US/docs/Glossary/Stringifier">Stringifier</a></li><li><a href="/en-US/docs/Glossary/STUN">STUN</a></li><li><a href="/en-US/docs/Glossary/Style_origin">Style origin</a></li><li><a href="/en-US/docs/Glossary/Stylesheet">Stylesheet</a></li><li><a href="/en-US/docs/Glossary/Submit_button">Submit button</a></li><li><a href="/en-US/docs/Glossary/SVG">SVG</a></li><li><a href="/en-US/docs/Glossary/SVN">SVN</a></li><li><a href="/en-US/docs/Glossary/Symbol">Symbol</a></li><li><a href="/en-US/docs/Glossary/Symmetric-key_cryptography">Symmetric-key cryptography</a></li><li><a href="/en-US/docs/Glossary/Synchronous">Synchronous</a></li><li><a href="/en-US/docs/Glossary/Syntax">Syntax</a></li><li><a href="/en-US/docs/Glossary/Syntax_error">Syntax error</a></li><li><a href="/en-US/docs/Glossary/Synthetic_monitoring">Synthetic monitoring</a></li><li><a href="/en-US/docs/Glossary/Table_Grid_Box">Table grid box</a></li><li><a href="/en-US/docs/Glossary/Table_Wrapper_Box">Table Wrapper Box</a></li><li><a href="/en-US/docs/Glossary/Tag">Tag</a></li><li><a href="/en-US/docs/Glossary/TCP">TCP</a></li><li><a href="/en-US/docs/Glossary/TCP_handshake">TCP handshake</a></li><li><a href="/en-US/docs/Glossary/TCP_slow_start">TCP slow start</a></li><li><a href="/en-US/docs/Glossary/Telnet">Telnet</a></li><li><a href="/en-US/docs/Glossary/Texel">Texel</a></li><li><a href="/en-US/docs/Glossary/Khronos">The Khronos Group</a></li><li><a href="/en-US/docs/Glossary/Thread">Thread</a></li><li><a href="/en-US/docs/Glossary/Three_js">Three js</a></li><li><a href="/en-US/docs/Glossary/Throttle">Throttle</a></li><li><a href="/en-US/docs/Glossary/Time_to_first_byte">Time to first byte</a></li><li><a href="/en-US/docs/Glossary/Time_to_interactive">Time to interactive</a></li><li><a href="/en-US/docs/Glossary/TLD">TLD</a></li><li><a href="/en-US/docs/Glossary/TOFU">TOFU</a></li><li><a href="/en-US/docs/Glossary/Top_layer">Top layer</a></li><li><a href="/en-US/docs/Glossary/Transient_activation">Transient activation</a></li><li><a href="/en-US/docs/Glossary/TLS">Transport Layer Security (TLS)</a></li><li><a href="/en-US/docs/Glossary/Tree_shaking">Tree shaking</a></li><li><a href="/en-US/docs/Glossary/Trident">Trident</a></li><li><a href="/en-US/docs/Glossary/Truthy">Truthy</a></li><li><a href="/en-US/docs/Glossary/TTL">TTL</a></li><li><a href="/en-US/docs/Glossary/TURN">TURN</a></li><li><a href="/en-US/docs/Glossary/Type">Type</a></li><li><a href="/en-US/docs/Glossary/Type_coercion">Type coercion</a></li><li><a href="/en-US/docs/Glossary/Type_Conversion">Type conversion</a></li><li><a href="/en-US/docs/Glossary/TypeScript">TypeScript</a></li><li><a href="/en-US/docs/Glossary/UAAG">UAAG</a></li><li><a href="/en-US/docs/Glossary/UDP">UDP (User Datagram Protocol)</a></li><li><a href="/en-US/docs/Glossary/UI">UI</a></li><li><a href="/en-US/docs/Glossary/Undefined">Undefined</a></li><li><a href="/en-US/docs/Glossary/Unicode">Unicode</a></li><li><a href="/en-US/docs/Glossary/Unix_time">Unix time</a></li><li><a href="/en-US/docs/Glossary/URI">URI</a></li><li><a href="/en-US/docs/Glossary/URL">URL</a></li><li><a href="/en-US/docs/Glossary/URN">URN</a></li><li><a href="/en-US/docs/Glossary/Usenet">Usenet</a></li><li><a href="/en-US/docs/Glossary/User_agent">User agent</a></li><li><a href="/en-US/docs/Glossary/UTF-8">UTF-8</a></li><li><a href="/en-US/docs/Glossary/UUID">UUID</a></li><li><a href="/en-US/docs/Glossary/UX">UX</a></li><li><a href="/en-US/docs/Glossary/Validator">Validator</a></li><li><a href="/en-US/docs/Glossary/Value">Value</a></li><li><a href="/en-US/docs/Glossary/Variable">Variable</a></li><li><a href="/en-US/docs/Glossary/Vendor_Prefix">Vendor Prefix</a></li><li><a href="/en-US/docs/Glossary/Viewport">Viewport</a></li><li><a href="/en-US/docs/Glossary/Visual_Viewport">Visual Viewport</a></li><li><a href="/en-US/docs/Glossary/Void_element">Void element</a></li><li><a href="/en-US/docs/Glossary/VoIP">VoIP</a></li><li><a href="/en-US/docs/Glossary/W3C">W3C</a></li><li><a href="/en-US/docs/Glossary/WAI">WAI</a></li><li><a href="/en-US/docs/Glossary/WCAG">WCAG</a></li><li><a href="/en-US/docs/Glossary/Web_performance">Web performance</a></li><li><a href="/en-US/docs/Glossary/Web_server">Web server</a></li><li><a href="/en-US/docs/Glossary/Web_standards">Web standards</a></li><li><a href="/en-US/docs/Glossary/WebAssembly">WebAssembly</a></li><li><a href="/en-US/docs/Glossary/WebDAV">WebDAV</a></li><li><a href="/en-US/docs/Glossary/WebExtensions">WebExtensions</a></li><li><a href="/en-US/docs/Glossary/WebGL">WebGL</a></li><li><a href="/en-US/docs/Glossary/WebIDL">WebIDL</a></li><li><a href="/en-US/docs/Glossary/WebKit">WebKit</a></li><li><a href="/en-US/docs/Glossary/WebM">WebM</a></li><li><a href="/en-US/docs/Glossary/WebP">WebP</a></li><li><a href="/en-US/docs/Glossary/WebRTC">WebRTC</a></li><li><a href="/en-US/docs/Glossary/WebSockets">WebSockets</a></li><li><a href="/en-US/docs/Glossary/WebVTT">WebVTT</a></li><li><a href="/en-US/docs/Glossary/WHATWG">WHATWG</a></li><li><a href="/en-US/docs/Glossary/Whitespace">Whitespace</a></li><li><a href="/en-US/docs/Glossary/WindowProxy">WindowProxy</a></li><li><a href="/en-US/docs/Glossary/World_Wide_Web">World Wide Web</a></li><li><a href="/en-US/docs/Glossary/Wrapper">Wrapper</a></li><li><a href="/en-US/docs/Glossary/XForms">XForms</a><abbr class="icon icon-deprecated" title="Deprecated. Not for use in new websites."> <span class="visually-hidden">Deprecated</span> </abbr></li><li><a href="/en-US/docs/Glossary/XHTML">XHTML</a></li><li><a href="/en-US/docs/Glossary/XInclude">XInclude</a></li><li><a href="/en-US/docs/Glossary/XLink">XLink</a></li><li><a href="/en-US/docs/Glossary/XML">XML</a></li><li><a href="/en-US/docs/Glossary/XMLHttpRequest">XMLHttpRequest (XHR)</a></li><li><a href="/en-US/docs/Glossary/XPath">XPath</a></li><li><a href="/en-US/docs/Glossary/XQuery">XQuery</a></li><li><a href="/en-US/docs/Glossary/XSLT">XSLT</a></li><li><a href="/en-US/docs/Glossary/Zstandard_compression">Zstandard compression</a></li></ol> </li> </ol> </div></div><section class="place side"></section></nav></aside><div class="toc-container"><aside class="toc"><nav><div class="document-toc-container"><section class="document-toc"><header><h2 class="document-toc-heading">In this article</h2></header><ul class="document-toc-list"><li class="document-toc-item "><a class="document-toc-link" href="#see_also">See also</a></li></ul></section></div></nav></aside><section class="place side"></section></div></div><main id="content" class="main-content "><article class="main-page-content" lang="en-US"><header><h1>Function</h1></header><div class="section-content"><p>A <strong>function</strong> is a code snippet that can be called by other code or by itself, or a <a href="/en-US/docs/Glossary/Variable">variable</a> that refers to the function. When a function is called, <a href="/en-US/docs/Glossary/Argument">arguments</a> are passed to the function as input, and the function can optionally return a value. A function in <a href="/en-US/docs/Glossary/JavaScript">JavaScript</a> is also an <a href="/en-US/docs/Glossary/Object">object</a>.</p> <p>A function name is an <a href="/en-US/docs/Glossary/Identifier">identifier</a> included as part of a function declaration or function expression. The function name's <a href="/en-US/docs/Glossary/Scope">scope</a> depends on whether the function name is a declaration or expression.</p></div><section aria-labelledby="different_types_of_functions"><h3 id="different_types_of_functions"><a href="#different_types_of_functions">Different types of functions</a></h3><div class="section-content"><p>An <strong>anonymous function</strong> is a function without a function name. Only function expressions can be anonymous, function declarations must have a name:</p> <div class="code-example"><div class="example-header"><span class="language-name">js</span></div><pre class="brush: js notranslate"><code>// Anonymous function created as a function expression (function () {}); // Anonymous function created as an arrow function () => {}; </code></pre></div> <p>The following terms are not used in the ECMAScript language specification, they're jargon used to refer to different types of functions.</p> <p>A <strong>named function</strong> is a function with a function name:</p> <div class="code-example"><div class="example-header"><span class="language-name">js</span></div><pre class="brush: js notranslate"><code>// Function declaration function foo() {} // Named function expression (function bar() {}); // Arrow function const baz = () => {}; </code></pre></div> <p>An <strong>inner function</strong> is a function inside another function (<code>square</code> in this case). An <strong>outer function</strong> is a function containing a function (<code>addSquares</code> in this case):</p> <div class="code-example"><div class="example-header"><span class="language-name">js</span></div><pre class="brush: js notranslate"><code>function addSquares(a, b) { function square(x) { return x * x; } return square(a) + square(b); } // Arrow function const addSquares2 = (a, b) => { const square = (x) => x * x; return square(a) + square(b); }; </code></pre></div> <p>A <strong>recursive function</strong> is a function that calls itself. See <a href="/en-US/docs/Glossary/Recursion">recursion</a>.</p> <div class="code-example"><div class="example-header"><span class="language-name">js</span></div><pre class="brush: js notranslate"><code>function loop(x) { if (x >= 10) return; loop(x + 1); } // Arrow function const loop2 = (x) => { if (x >= 10) return; loop(x + 1); }; </code></pre></div> <p>An <strong>Immediately Invoked Function Expression</strong> (<a href="/en-US/docs/Glossary/IIFE">IIFE</a>) is a function that is called directly after the function is loaded into the browser's compiler. The way to identify an IIFE is by locating the extra left and right parenthesis at the end of the function's definition.</p> <p>Function expressions, named or anonymous, can be called immediately.</p> <div class="code-example"><div class="example-header"><span class="language-name">js</span></div><pre class="brush: js notranslate"><code>(function foo() { console.log("Hello Foo"); })(); (function food() { console.log("Hello Food"); })(); (() => console.log("hello world"))(); </code></pre></div> <p>Declared functions can't be called immediately this way, because IIFEs must be function <em>expressions</em>.</p> <div class="code-example"><div class="example-header"><span class="language-name">js</span></div><pre class="brush: js example-bad notranslate"><code>function foo() { console.log('Hello Foo'); }(); </code></pre></div> <p>If you'd like to know more about IIFEs, check out the following page on Wikipedia: <a href="https://en.wikipedia.org/wiki/Immediately_invoked_function_expression" class="external" target="_blank">Immediately Invoked Function Expression</a></p></div></section><section aria-labelledby="see_also"><h2 id="see_also"><a href="#see_also">See also</a></h2><div class="section-content"><ul> <li><a href="/en-US/docs/Web/JavaScript/Guide/Functions">Functions</a></li> <li><a href="/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions">Arrow Functions</a></li> </ul></div></section></article><aside class="article-footer"><div class="article-footer-inner"><div class="svg-container"><svg xmlns="http://www.w3.org/2000/svg" width="162" height="162" viewBox="0 0 162 162" fill="none" role="none"><mask id="b" fill="#fff"><path d="M97.203 47.04c8.113-7.886 18.004-13.871 28.906-17.492a78 78 0 0 1 33.969-3.39c11.443 1.39 22.401 5.295 32.024 11.411s17.656 14.28 23.476 23.86c5.819 9.579 9.269 20.318 10.083 31.385a69.85 69.85 0 0 1-5.387 32.44c-4.358 10.272-11.115 19.443-19.747 26.801-8.632 7.359-18.908 12.709-30.034 15.637l-6.17-21.698c7.666-2.017 14.746-5.703 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href=\"/en-US/docs/Glossary/Browsing_context\">Browsing context</a></li><li><a href=\"/en-US/docs/Glossary/Buffer\">Buffer</a></li><li><a href=\"/en-US/docs/Glossary/Cache\">Cache</a></li><li><a href=\"/en-US/docs/Glossary/Cacheable\">Cacheable</a></li><li><a href=\"/en-US/docs/Glossary/CalDAV\">CalDAV</a></li><li><a href=\"/en-US/docs/Glossary/Call_stack\">Call stack</a></li><li><a href=\"/en-US/docs/Glossary/Callback_function\">Callback function</a></li><li><a href=\"/en-US/docs/Glossary/Camel_case\">Camel case</a></li><li><a href=\"/en-US/docs/Glossary/Canonical_order\">Canonical order</a></li><li><a href=\"/en-US/docs/Glossary/Canvas\">Canvas</a></li><li><a href=\"/en-US/docs/Glossary/Card_sorting\">Card sorting</a></li><li><a href=\"/en-US/docs/Glossary/CardDAV\">CardDAV</a></li><li><a href=\"/en-US/docs/Glossary/Caret\">Caret</a></li><li><a href=\"/en-US/docs/Glossary/CDN\">CDN</a></li><li><a href=\"/en-US/docs/Glossary/Certificate_authority\">Certificate authority</a></li><li><a href=\"/en-US/docs/Glossary/Certified\">Certified</a></li><li><a href=\"/en-US/docs/Glossary/Challenge\">Challenge-response authentication</a></li><li><a href=\"/en-US/docs/Glossary/Character\">Character</a></li><li><a href=\"/en-US/docs/Glossary/Character_encoding\">Character encoding</a></li><li><a href=\"/en-US/docs/Glossary/Character_reference\">Character reference</a></li><li><a href=\"/en-US/docs/Glossary/Character_set\">Character set</a></li><li><a href=\"/en-US/docs/Glossary/Chrome\">Chrome</a></li><li><a href=\"/en-US/docs/Glossary/CIA\">CIA</a></li><li><a href=\"/en-US/docs/Glossary/Cipher\">Cipher</a></li><li><a href=\"/en-US/docs/Glossary/Cipher_suite\">Cipher suite</a></li><li><a href=\"/en-US/docs/Glossary/Ciphertext\">Ciphertext</a></li><li><a href=\"/en-US/docs/Glossary/Class\">Class</a></li><li><a href=\"/en-US/docs/Glossary/Clickjacking\">Clickjacking</a></li><li><a href=\"/en-US/docs/Glossary/Closure\">Closure</a></li><li><a href=\"/en-US/docs/Glossary/Cloud\">Cloud</a></li><li><a href=\"/en-US/docs/Glossary/Cloud_computing\">Cloud computing</a></li><li><a href=\"/en-US/docs/Glossary/CMS\">CMS</a></li><li><a href=\"/en-US/docs/Glossary/Code_point\">Code point</a></li><li><a href=\"/en-US/docs/Glossary/Code_splitting\">Code splitting</a></li><li><a href=\"/en-US/docs/Glossary/Code_unit\">Code unit</a></li><li><a href=\"/en-US/docs/Glossary/Codec\">Codec</a></li><li><a href=\"/en-US/docs/Glossary/Color_space\">Color space</a></li><li><a href=\"/en-US/docs/Glossary/Color_wheel\">Color wheel</a></li><li><a href=\"/en-US/docs/Glossary/Compile\">Compile</a></li><li><a href=\"/en-US/docs/Glossary/Compile_time\">Compile time</a></li><li><a href=\"/en-US/docs/Glossary/Composite_operation\">Composite operation</a></li><li><a href=\"/en-US/docs/Glossary/Computer_Programming\">Computer Programming</a></li><li><a href=\"/en-US/docs/Glossary/Conditional\">Conditional</a></li><li><a href=\"/en-US/docs/Glossary/Constant\">Constant</a></li><li><a href=\"/en-US/docs/Glossary/Constructor\">Constructor</a></li><li><a href=\"/en-US/docs/Glossary/Content_header\">Content header</a></li><li><a href=\"/en-US/docs/Glossary/Continuous_Media\">Continuous Media</a></li><li><a href=\"/en-US/docs/Glossary/Control_flow\">Control flow</a></li><li><a href=\"/en-US/docs/Glossary/Cookie\">Cookie</a></li><li><a href=\"/en-US/docs/Glossary/Copyleft\">Copyleft</a></li><li><a href=\"/en-US/docs/Glossary/CORS\">CORS</a></li><li><a href=\"/en-US/docs/Glossary/CORS-safelisted_request_header\">CORS-safelisted request header</a></li><li><a href=\"/en-US/docs/Glossary/CORS-safelisted_response_header\">CORS-safelisted response header</a></li><li><a href=\"/en-US/docs/Glossary/Crawler\">Crawler</a></li><li><a href=\"/en-US/docs/Glossary/Credential\">Credential</a></li><li><a href=\"/en-US/docs/Glossary/CRLF\">CRLF</a></li><li><a href=\"/en-US/docs/Glossary/Cross_Axis\">Cross Axis</a></li><li><a href=\"/en-US/docs/Glossary/Cross-site_scripting\">Cross-site scripting (XSS)</a></li><li><a href=\"/en-US/docs/Glossary/CRUD\">CRUD</a></li><li><a href=\"/en-US/docs/Glossary/Cryptanalysis\">Cryptanalysis</a></li><li><a href=\"/en-US/docs/Glossary/Cryptographic_hash_function\">Cryptographic hash function</a></li><li><a href=\"/en-US/docs/Glossary/Cryptography\">Cryptography</a></li><li><a href=\"/en-US/docs/Glossary/CSP\">CSP</a></li><li><a href=\"/en-US/docs/Glossary/CSRF\">CSRF</a></li><li><a href=\"/en-US/docs/Glossary/CSS\">CSS</a></li><li><a href=\"/en-US/docs/Glossary/CSSOM\">CSS Object Model (CSSOM)</a></li><li><a href=\"/en-US/docs/Glossary/CSS_pixel\">CSS pixel</a></li><li><a href=\"/en-US/docs/Glossary/CSS_preprocessor\">CSS preprocessor</a></li><li><a href=\"/en-US/docs/Glossary/CLS\">Cumulative Layout Shift (CLS)</a></li><li><a href=\"/en-US/docs/Glossary/Data_structure\">Data structure</a></li><li><a href=\"/en-US/docs/Glossary/Database\">Database</a></li><li><a href=\"/en-US/docs/Glossary/Debounce\">Debounce</a></li><li><a href=\"/en-US/docs/Glossary/Decryption\">Decryption</a></li><li><a href=\"/en-US/docs/Glossary/Deep_copy\">Deep copy</a></li><li><a href=\"/en-US/docs/Glossary/Delta\">Delta</a></li><li><a href=\"/en-US/docs/Glossary/Denial_of_Service\">Denial of Service</a></li><li><a href=\"/en-US/docs/Glossary/Deno\">Deno</a></li><li><a href=\"/en-US/docs/Glossary/CSS_Descriptor\">Descriptor (CSS)</a></li><li><a href=\"/en-US/docs/Glossary/Deserialization\">Deserialization</a></li><li><a href=\"/en-US/docs/Glossary/Developer_Tools\">Developer Tools</a></li><li><a href=\"/en-US/docs/Glossary/Digest\">Digest</a></li><li><a href=\"/en-US/docs/Glossary/Digital_certificate\">Digital certificate</a></li><li><a href=\"/en-US/docs/Glossary/Digital_signature\">Digital signature</a></li><li><a href=\"/en-US/docs/Glossary/Distributed_Denial_of_Service\">Distributed Denial of Service</a></li><li><a href=\"/en-US/docs/Glossary/DMZ\">DMZ</a></li><li><a href=\"/en-US/docs/Glossary/DNS\">DNS</a></li><li><a href=\"/en-US/docs/Glossary/Doctype\">Doctype</a></li><li><a href=\"/en-US/docs/Glossary/Document_directive\">Document directive</a></li><li><a href=\"/en-US/docs/Glossary/Document_environment\">Document environment</a></li><li><a href=\"/en-US/docs/Glossary/DOM\">DOM (Document Object Model)</a></li><li><a href=\"/en-US/docs/Glossary/Domain\">Domain</a></li><li><a href=\"/en-US/docs/Glossary/Domain_name\">Domain name</a></li><li><a href=\"/en-US/docs/Glossary/Domain_sharding\">Domain sharding</a></li><li><a href=\"/en-US/docs/Glossary/Dominator\">Dominator</a></li><li><a href=\"/en-US/docs/Glossary/DOS_attack\">DoS attack</a></li><li><a href=\"/en-US/docs/Glossary/DSL\">DSL</a></li><li><a href=\"/en-US/docs/Glossary/DTLS\">DTLS (Datagram Transport Layer Security)</a></li><li><a href=\"/en-US/docs/Glossary/DTMF\">DTMF (Dual-Tone Multi-Frequency signaling)</a></li><li><a href=\"/en-US/docs/Glossary/Dynamic_typing\">Dynamic typing</a></li><li><a href=\"/en-US/docs/Glossary/ECMA\">ECMA</a></li><li><a href=\"/en-US/docs/Glossary/ECMAScript\">ECMAScript</a></li><li><a href=\"/en-US/docs/Glossary/Effective_connection_type\">Effective connection type</a></li><li><a href=\"/en-US/docs/Glossary/Element\">Element</a></li><li><a href=\"/en-US/docs/Glossary/Encapsulation\">Encapsulation</a></li><li><a href=\"/en-US/docs/Glossary/Encryption\">Encryption</a></li><li><a href=\"/en-US/docs/Glossary/Endianness\">Endianness</a></li><li><a href=\"/en-US/docs/Glossary/Engine\">Engine</a></li><li><a href=\"/en-US/docs/Glossary/Entity\">Entity</a></li><li><a href=\"/en-US/docs/Glossary/Entity_header\">Entity header</a></li><li><a href=\"/en-US/docs/Glossary/Enumerated\">Enumerated</a></li><li><a href=\"/en-US/docs/Glossary/eTLD\">eTLD</a></li><li><a href=\"/en-US/docs/Glossary/Event\">Event</a></li><li><a href=\"/en-US/docs/Glossary/Exception\">Exception</a></li><li><a href=\"/en-US/docs/Glossary/EXIF\">EXIF</a></li><li><a href=\"/en-US/docs/Glossary/Expando\">Expando</a></li><li><a href=\"/en-US/docs/Glossary/Fallback_Alignment\">Fallback alignment</a></li><li><a href=\"/en-US/docs/Glossary/Falsy\">Falsy</a></li><li><a href=\"/en-US/docs/Glossary/Favicon\">Favicon</a></li><li><a href=\"/en-US/docs/Glossary/Federated_identity\">Federated identity</a></li><li><a href=\"/en-US/docs/Glossary/Fetch_directive\">Fetch directive</a></li><li><a href=\"/en-US/docs/Glossary/Fetch_metadata_request_header\">Fetch metadata request header</a></li><li><a href=\"/en-US/docs/Glossary/Fingerprinting\">Fingerprinting</a></li><li><a href=\"/en-US/docs/Glossary/Firefox_OS\">Firefox OS</a></li><li><a href=\"/en-US/docs/Glossary/Firewall\">Firewall</a></li><li><a href=\"/en-US/docs/Glossary/First_contentful_paint\">First Contentful Paint (FCP)</a></li><li><a href=\"/en-US/docs/Glossary/First_CPU_idle\">First CPU idle</a></li><li><a href=\"/en-US/docs/Glossary/First_input_delay\">First Input Delay (FID)</a><abbr class=\"icon icon-deprecated\" title=\"Deprecated. Not for use in new websites.\">\n <span class=\"visually-hidden\">Deprecated</span>\n</abbr></li><li><a href=\"/en-US/docs/Glossary/First_meaningful_paint\">First Meaningful Paint (FMP)</a></li><li><a href=\"/en-US/docs/Glossary/First_paint\">First Paint (FP)</a></li><li><a href=\"/en-US/docs/Glossary/First-class_Function\">First-class Function</a></li><li><a href=\"/en-US/docs/Glossary/Flex\">Flex</a></li><li><a href=\"/en-US/docs/Glossary/Flex_Container\">Flex Container</a></li><li><a href=\"/en-US/docs/Glossary/Flex_Item\">Flex Item</a></li><li><a href=\"/en-US/docs/Glossary/Flexbox\">Flexbox</a></li><li><a href=\"/en-US/docs/Glossary/Flow_relative_values\">Flow relative values</a></li><li><a href=\"/en-US/docs/Glossary/Forbidden_header_name\">Forbidden header name</a></li><li><a href=\"/en-US/docs/Glossary/Forbidden_response_header_name\">Forbidden response header name</a></li><li><a href=\"/en-US/docs/Glossary/Fork\">Fork</a></li><li><a href=\"/en-US/docs/Glossary/Fragmentainer\">Fragmentainer</a></li><li><a href=\"/en-US/docs/Glossary/FPS\">Frame rate (FPS)</a></li><li><a href=\"/en-US/docs/Glossary/FTP\">FTP</a></li><li><a href=\"/en-US/docs/Glossary/FTU\">FTU</a></li><li><em><a href=\"/en-US/docs/Glossary/Function\" aria-current=\"page\">Function</a></em></li><li><a href=\"/en-US/docs/Glossary/Fuzzing\">Fuzz testing</a></li><li><a href=\"/en-US/docs/Glossary/Gamut\">Gamut</a></li><li><a href=\"/en-US/docs/Glossary/Garbage_collection\">Garbage collection</a></li><li><a href=\"/en-US/docs/Glossary/Gecko\">Gecko</a></li><li><a href=\"/en-US/docs/Glossary/General_header\">General header</a></li><li><a href=\"/en-US/docs/Glossary/GIF\">GIF</a></li><li><a href=\"/en-US/docs/Glossary/Git\">Git</a></li><li><a href=\"/en-US/docs/Glossary/Global_object\">Global object</a></li><li><a href=\"/en-US/docs/Glossary/Global_scope\">Global scope</a></li><li><a href=\"/en-US/docs/Glossary/Global_variable\">Global variable</a></li><li><a href=\"/en-US/docs/Glossary/Glyph\">Glyph</a></li><li><a href=\"/en-US/docs/Glossary/Google_Chrome\">Google Chrome</a></li><li><a href=\"/en-US/docs/Glossary/GPL\">GPL</a></li><li><a href=\"/en-US/docs/Glossary/GPU\">GPU</a></li><li><a href=\"/en-US/docs/Glossary/Graceful_degradation\">Graceful degradation</a></li><li><a href=\"/en-US/docs/Glossary/Grid\">Grid</a></li><li><a href=\"/en-US/docs/Glossary/Grid_Areas\">Grid Areas</a></li><li><a href=\"/en-US/docs/Glossary/Grid_Axis\">Grid Axis</a></li><li><a href=\"/en-US/docs/Glossary/Grid_Cell\">Grid Cell</a></li><li><a href=\"/en-US/docs/Glossary/Grid_Column\">Grid Column</a></li><li><a href=\"/en-US/docs/Glossary/Grid_Container\">Grid container</a></li><li><a href=\"/en-US/docs/Glossary/Grid_Lines\">Grid Lines</a></li><li><a href=\"/en-US/docs/Glossary/Grid_Row\">Grid Row</a></li><li><a href=\"/en-US/docs/Glossary/Grid_Tracks\">Grid Tracks</a></li><li><a href=\"/en-US/docs/Glossary/Gutters\">Gutters</a></li><li><a href=\"/en-US/docs/Glossary/gzip_compression\">gzip compression</a></li><li><a href=\"/en-US/docs/Glossary/Hash\">Hash</a></li><li><a href=\"/en-US/docs/Glossary/Head\">Head</a></li><li><a href=\"/en-US/docs/Glossary/High-level_programming_language\">High-level programming language</a></li><li><a href=\"/en-US/docs/Glossary/HMAC\">HMAC</a></li><li><a href=\"/en-US/docs/Glossary/Hoisting\">Hoisting</a></li><li><a href=\"/en-US/docs/Glossary/Host\">Host</a></li><li><a href=\"/en-US/docs/Glossary/Hotlink\">Hotlink</a></li><li><a href=\"/en-US/docs/Glossary/Houdini\">Houdini</a></li><li><a href=\"/en-US/docs/Glossary/HPKP\">HPKP</a></li><li><a href=\"/en-US/docs/Glossary/HSTS\">HSTS</a></li><li><a href=\"/en-US/docs/Glossary/HTML\">HTML</a></li><li><a href=\"/en-US/docs/Glossary/html_color_codes\">HTML color codes</a></li><li><a href=\"/en-US/docs/Glossary/HTML5\">HTML5</a></li><li><a href=\"/en-US/docs/Glossary/HTTP\">HTTP</a></li><li><a href=\"/en-US/docs/Glossary/HTTP_Content\">HTTP Content</a></li><li><a href=\"/en-US/docs/Glossary/HTTP_header\">HTTP header</a></li><li><a href=\"/en-US/docs/Glossary/HTTP_2\">HTTP/2</a></li><li><a href=\"/en-US/docs/Glossary/HTTP_3\">HTTP/3</a></li><li><a href=\"/en-US/docs/Glossary/HTTPS\">HTTPS</a></li><li><a href=\"/en-US/docs/Glossary/HTTPS_RR\">HTTPS RR</a></li><li><a href=\"/en-US/docs/Glossary/Hyperlink\">Hyperlink</a></li><li><a href=\"/en-US/docs/Glossary/Hypertext\">Hypertext</a></li><li><a href=\"/en-US/docs/Glossary/IANA\">IANA</a></li><li><a href=\"/en-US/docs/Glossary/ICANN\">ICANN</a></li><li><a href=\"/en-US/docs/Glossary/ICE\">ICE</a></li><li><a href=\"/en-US/docs/Glossary/IDE\">IDE</a></li><li><a href=\"/en-US/docs/Glossary/Idempotent\">Idempotent</a></li><li><a href=\"/en-US/docs/Glossary/Identifier\">Identifier</a></li><li><a href=\"/en-US/docs/Glossary/Identity_provider\">Identity provider (IdP)</a></li><li><a href=\"/en-US/docs/Glossary/IDL\">IDL</a></li><li><a href=\"/en-US/docs/Glossary/IETF\">IETF</a></li><li><a href=\"/en-US/docs/Glossary/IIFE\">IIFE</a></li><li><a href=\"/en-US/docs/Glossary/IMAP\">IMAP</a></li><li><a href=\"/en-US/docs/Glossary/Immutable\">Immutable</a></li><li><a href=\"/en-US/docs/Glossary/IndexedDB\">IndexedDB</a></li><li><a href=\"/en-US/docs/Glossary/Information_architecture\">Information architecture</a></li><li><a href=\"/en-US/docs/Glossary/Inheritance\">Inheritance</a></li><li><a href=\"/en-US/docs/Glossary/Ink_overflow\">Ink overflow</a></li><li><a href=\"/en-US/docs/Glossary/Inline-level_content\">Inline-level content</a></li><li><a href=\"/en-US/docs/Glossary/Input_method_editor\">Input method editor</a></li><li><a href=\"/en-US/docs/Glossary/Inset_properties\">Inset properties</a></li><li><a href=\"/en-US/docs/Glossary/Instance\">Instance</a></li><li><a href=\"/en-US/docs/Glossary/Interaction_to_next_paint\">Interaction to Next Paint (INP)</a></li><li><a href=\"/en-US/docs/Glossary/Internationalization\">Internationalization (i18n)</a></li><li><a href=\"/en-US/docs/Glossary/Internet\">Internet</a></li><li><a href=\"/en-US/docs/Glossary/Interpolation\">Interpolation</a></li><li><a href=\"/en-US/docs/Glossary/Intrinsic_Size\">Intrinsic size</a></li><li><a href=\"/en-US/docs/Glossary/IP_Address\">IP Address</a></li><li><a href=\"/en-US/docs/Glossary/IPv4\">IPv4</a></li><li><a href=\"/en-US/docs/Glossary/IPv6\">IPv6</a></li><li><a href=\"/en-US/docs/Glossary/IRC\">IRC</a></li><li><a href=\"/en-US/docs/Glossary/ISO\">ISO</a></li><li><a href=\"/en-US/docs/Glossary/ISP\">ISP</a></li><li><a href=\"/en-US/docs/Glossary/ITU\">ITU</a></li><li><a href=\"/en-US/docs/Glossary/Jank\">Jank</a></li><li><a href=\"/en-US/docs/Glossary/Java\">Java</a></li><li><a href=\"/en-US/docs/Glossary/JavaScript\">JavaScript</a></li><li><a href=\"/en-US/docs/Glossary/Jitter\">Jitter</a></li><li><a href=\"/en-US/docs/Glossary/JPEG\">JPEG</a></li><li><a href=\"/en-US/docs/Glossary/JSON\">JSON</a></li><li><a href=\"/en-US/docs/Glossary/JSON_type_representation\">JSON type representation</a></li><li><a href=\"/en-US/docs/Glossary/Kebab_case\">Kebab case</a></li><li><a href=\"/en-US/docs/Glossary/Key\">Key</a></li><li><a href=\"/en-US/docs/Glossary/Keyword\">Keyword</a></li><li><a href=\"/en-US/docs/Glossary/Largest_contentful_paint\">Largest Contentful Paint (LCP)</a></li><li><a href=\"/en-US/docs/Glossary/Latency\">Latency</a></li><li><a href=\"/en-US/docs/Glossary/Layout_viewport\">Layout viewport</a></li><li><a href=\"/en-US/docs/Glossary/Lazy_load\">Lazy load</a></li><li><a href=\"/en-US/docs/Glossary/LGPL\">LGPL</a></li><li><a href=\"/en-US/docs/Glossary/Ligature\">Ligature</a></li><li><a href=\"/en-US/docs/Glossary/Literal\">Literal</a></li><li><a href=\"/en-US/docs/Glossary/Local_scope\">Local scope</a></li><li><a href=\"/en-US/docs/Glossary/Local_variable\">Local variable</a></li><li><a href=\"/en-US/docs/Glossary/Locale\">Locale</a></li><li><a href=\"/en-US/docs/Glossary/Localization\">Localization</a></li><li><a href=\"/en-US/docs/Glossary/Logical_properties\">Logical properties</a></li><li><a href=\"/en-US/docs/Glossary/Long_task\">Long task</a></li><li><a href=\"/en-US/docs/Glossary/Loop\">Loop</a></li><li><a href=\"/en-US/docs/Glossary/Lossless_compression\">Lossless compression</a></li><li><a href=\"/en-US/docs/Glossary/Lossy_compression\">Lossy compression</a></li><li><a href=\"/en-US/docs/Glossary/LTR\">LTR (Left To Right)</a></li><li><a href=\"/en-US/docs/Glossary/Main_Axis\">Main Axis</a></li><li><a href=\"/en-US/docs/Glossary/Main_thread\">Main thread</a></li><li><a href=\"/en-US/docs/Glossary/Markup\">Markup</a></li><li><a href=\"/en-US/docs/Glossary/MathML\">MathML</a></li><li><a href=\"/en-US/docs/Glossary/Media\">Media</a></li><li><a href=\"/en-US/docs/Glossary/Media_query\">Media query</a></li><li><a href=\"/en-US/docs/Glossary/Metadata\">Metadata</a></li><li><a href=\"/en-US/docs/Glossary/Method\">Method</a></li><li><a href=\"/en-US/docs/Glossary/Microsoft_Edge\">Microsoft Edge</a></li><li><a href=\"/en-US/docs/Glossary/Microsoft_Internet_Explorer\">Microsoft Internet Explorer</a></li><li><a href=\"/en-US/docs/Glossary/Middleware\">Middleware</a></li><li><a href=\"/en-US/docs/Glossary/MIME\">MIME</a></li><li><a href=\"/en-US/docs/Glossary/MIME_type\">MIME type</a></li><li><a href=\"/en-US/docs/Glossary/Minification\">Minification</a></li><li><a href=\"/en-US/docs/Glossary/MitM\">MitM</a></li><li><a href=\"/en-US/docs/Glossary/Mixin\">Mixin</a></li><li><a href=\"/en-US/docs/Glossary/Mobile_First\">Mobile First</a></li><li><a href=\"/en-US/docs/Glossary/Modem\">Modem</a></li><li><a href=\"/en-US/docs/Glossary/Modularity\">Modularity</a></li><li><a href=\"/en-US/docs/Glossary/Mozilla_Firefox\">Mozilla Firefox</a></li><li><a href=\"/en-US/docs/Glossary/Mutable\">Mutable</a></li><li><a href=\"/en-US/docs/Glossary/MVC\">MVC</a></li><li><a href=\"/en-US/docs/Glossary/Namespace\">Namespace</a></li><li><a href=\"/en-US/docs/Glossary/NaN\">NaN</a></li><li><a href=\"/en-US/docs/Glossary/NAT\">NAT</a></li><li><a href=\"/en-US/docs/Glossary/Native\">Native</a></li><li><a href=\"/en-US/docs/Glossary/Navigation_directive\">Navigation directive</a></li><li><a href=\"/en-US/docs/Glossary/Netscape_Navigator\">Netscape Navigator</a></li><li><a href=\"/en-US/docs/Glossary/Network_throttling\">Network throttling</a></li><li><a href=\"/en-US/docs/Glossary/NNTP\">NNTP</a></li><li><a href=\"/en-US/docs/Glossary/Node\">Node</a></li><li><a href=\"/en-US/docs/Glossary/Node.js\">Node.js</a></li><li><a href=\"/en-US/docs/Glossary/Non-normative\">Non-normative</a></li><li><a href=\"/en-US/docs/Glossary/Normative\">Normative</a></li><li><a href=\"/en-US/docs/Glossary/Null\">Null</a></li><li><a href=\"/en-US/docs/Glossary/Nullish\">Nullish value</a></li><li><a href=\"/en-US/docs/Glossary/Number\">Number</a></li><li><a href=\"/en-US/docs/Glossary/Object\">Object</a></li><li><a href=\"/en-US/docs/Glossary/Object_reference\">Object reference</a></li><li><a href=\"/en-US/docs/Glossary/OOP\">OOP</a></li><li><a href=\"/en-US/docs/Glossary/OpenGL\">OpenGL</a></li><li><a href=\"/en-US/docs/Glossary/OpenSSL\">OpenSSL</a></li><li><a href=\"/en-US/docs/Glossary/Opera_Browser\">Opera Browser</a></li><li><a href=\"/en-US/docs/Glossary/Operand\">Operand</a></li><li><a href=\"/en-US/docs/Glossary/Operator\">Operator</a></li><li><a href=\"/en-US/docs/Glossary/Origin\">Origin</a></li><li><a href=\"/en-US/docs/Glossary/OTA\">OTA</a></li><li><a href=\"/en-US/docs/Glossary/OWASP\">OWASP</a></li><li><a href=\"/en-US/docs/Glossary/P2P\">P2P</a></li><li><a href=\"/en-US/docs/Glossary/PAC\">PAC</a></li><li><a href=\"/en-US/docs/Glossary/Packet\">Packet</a></li><li><a href=\"/en-US/docs/Glossary/Page_load_time\">Page load time</a></li><li><a href=\"/en-US/docs/Glossary/Page_prediction\">Page prediction</a></li><li><a href=\"/en-US/docs/Glossary/Parameter\">Parameter</a></li><li><a href=\"/en-US/docs/Glossary/Parent_object\">Parent object</a></li><li><a href=\"/en-US/docs/Glossary/Parse\">Parse</a></li><li><a href=\"/en-US/docs/Glossary/Parser\">Parser</a></li><li><a href=\"/en-US/docs/Glossary/Payload_body\">Payload body</a></li><li><a href=\"/en-US/docs/Glossary/Payload_header\">Payload header</a></li><li><a href=\"/en-US/docs/Glossary/PDF\">PDF</a></li><li><a href=\"/en-US/docs/Glossary/Perceived_performance\">Perceived performance</a></li><li><a href=\"/en-US/docs/Glossary/Percent-encoding\">Percent-encoding</a></li><li><a href=\"/en-US/docs/Glossary/PHP\">PHP</a></li><li><a href=\"/en-US/docs/Glossary/Physical_properties\">Physical properties</a></li><li><a href=\"/en-US/docs/Glossary/Pixel\">Pixel</a></li><li><a href=\"/en-US/docs/Glossary/Placeholder_names\">Placeholder names</a></li><li><a href=\"/en-US/docs/Glossary/Plaintext\">Plaintext</a></li><li><a href=\"/en-US/docs/Glossary/Plugin\">Plugin</a></li><li><a href=\"/en-US/docs/Glossary/PNG\">PNG</a></li><li><a href=\"/en-US/docs/Glossary/Polyfill\">Polyfill</a></li><li><a href=\"/en-US/docs/Glossary/Polymorphism\">Polymorphism</a></li><li><a href=\"/en-US/docs/Glossary/POP\">POP3</a></li><li><a href=\"/en-US/docs/Glossary/Port\">Port</a></li><li><a href=\"/en-US/docs/Glossary/Prefetch\">Prefetch</a></li><li><a href=\"/en-US/docs/Glossary/Preflight_request\">Preflight request</a></li><li><a href=\"/en-US/docs/Glossary/Prerender\">Prerender</a></li><li><a href=\"/en-US/docs/Glossary/Presto\">Presto</a></li><li><a href=\"/en-US/docs/Glossary/Primitive\">Primitive</a></li><li><a href=\"/en-US/docs/Glossary/Privileged\">Privileged</a></li><li><a href=\"/en-US/docs/Glossary/Privileged_code\">Privileged code</a></li><li><a href=\"/en-US/docs/Glossary/Progressive_Enhancement\">Progressive Enhancement</a></li><li><a href=\"/en-US/docs/Glossary/Progressive_web_apps\">Progressive web apps</a></li><li><a href=\"/en-US/docs/Glossary/Promise\">Promise</a></li><li><a href=\"/en-US/docs/Glossary/Property\">Property</a></li><li><a href=\"/en-US/docs/Glossary/Protocol\">Protocol</a></li><li><a href=\"/en-US/docs/Glossary/Prototype\">Prototype</a></li><li><a href=\"/en-US/docs/Glossary/Prototype-based_programming\">Prototype-based programming</a></li><li><a href=\"/en-US/docs/Glossary/Proxy_server\">Proxy server</a></li><li><a href=\"/en-US/docs/Glossary/Pseudo-class\">Pseudo-class</a></li><li><a href=\"/en-US/docs/Glossary/Pseudo-element\">Pseudo-element</a></li><li><a href=\"/en-US/docs/Glossary/Pseudocode\">Pseudocode</a></li><li><a href=\"/en-US/docs/Glossary/Public-key_cryptography\">Public-key cryptography</a></li><li><a href=\"/en-US/docs/Glossary/Python\">Python</a></li><li><a href=\"/en-US/docs/Glossary/Quality_values\">Quality values</a></li><li><a href=\"/en-US/docs/Glossary/Quaternion\">Quaternion</a></li><li><a href=\"/en-US/docs/Glossary/QUIC\">QUIC</a></li><li><a href=\"/en-US/docs/Glossary/RAIL\">RAIL</a></li><li><a href=\"/en-US/docs/Glossary/RNG\">Random Number Generator</a></li><li><a href=\"/en-US/docs/Glossary/Raster_image\">Raster image</a></li><li><a href=\"/en-US/docs/Glossary/Rate_limit\">Rate limit</a></li><li><a href=\"/en-US/docs/Glossary/RDF\">RDF</a></li><li><a href=\"/en-US/docs/Glossary/Real_User_Monitoring\">Real User Monitoring (RUM)</a></li><li><a href=\"/en-US/docs/Glossary/Recursion\">Recursion</a></li><li><a href=\"/en-US/docs/Glossary/Reflow\">Reflow</a></li><li><a href=\"/en-US/docs/Glossary/Regular_expression\">Regular expression</a></li><li><a href=\"/en-US/docs/Glossary/Relying_party\">Relying party</a></li><li><a href=\"/en-US/docs/Glossary/Render_blocking\">Render-blocking</a></li><li><a href=\"/en-US/docs/Glossary/Repaint\">Repaint</a></li><li><a href=\"/en-US/docs/Glossary/Replay_attack\">Replay attack</a></li><li><a href=\"/en-US/docs/Glossary/Repo\">Repo</a></li><li><a href=\"/en-US/docs/Glossary/Reporting_directive\">Reporting directive</a></li><li><a href=\"/en-US/docs/Glossary/Representation_header\">Representation header</a></li><li><a href=\"/en-US/docs/Glossary/Request_header\">Request header</a></li><li><a href=\"/en-US/docs/Glossary/Resource_Timing\">Resource Timing</a></li><li><a href=\"/en-US/docs/Glossary/Response_header\">Response header</a></li><li><a href=\"/en-US/docs/Glossary/Responsive_web_design\">Responsive web design</a></li><li><a href=\"/en-US/docs/Glossary/REST\">REST</a></li><li><a href=\"/en-US/docs/Glossary/RGB\">RGB</a></li><li><a href=\"/en-US/docs/Glossary/RIL\">RIL</a></li><li><a href=\"/en-US/docs/Glossary/Robots.txt\">Robots.txt</a></li><li><a href=\"/en-US/docs/Glossary/Round_Trip_Time\">Round Trip Time (RTT)</a></li><li><a href=\"/en-US/docs/Glossary/Router\">Router</a></li><li><a href=\"/en-US/docs/Glossary/RSS\">RSS</a></li><li><a href=\"/en-US/docs/Glossary/Rsync\">Rsync</a></li><li><a href=\"/en-US/docs/Glossary/RTCP\">RTCP (RTP Control Protocol)</a></li><li><a href=\"/en-US/docs/Glossary/RTF\">RTF</a></li><li><a href=\"/en-US/docs/Glossary/RTL\">RTL (Right to Left)</a></li><li><a href=\"/en-US/docs/Glossary/RTP\">RTP (Real-time Transport Protocol) and SRTP (Secure RTP)</a></li><li><a href=\"/en-US/docs/Glossary/RTSP\">RTSP: Real-time streaming protocol</a></li><li><a href=\"/en-US/docs/Glossary/Ruby\">Ruby</a></li><li><a href=\"/en-US/docs/Glossary/Safe\">Safe</a></li><li><a href=\"/en-US/docs/Glossary/Salt\">Salt</a></li><li><a href=\"/en-US/docs/Glossary/Same-origin_policy\">Same-origin policy</a></li><li><a href=\"/en-US/docs/Glossary/SCM\">SCM</a></li><li><a href=\"/en-US/docs/Glossary/Scope\">Scope</a></li><li><a href=\"/en-US/docs/Glossary/Screen_reader\">Screen reader</a></li><li><a href=\"/en-US/docs/Glossary/Script-supporting_element\">Script-supporting element</a></li><li><a href=\"/en-US/docs/Glossary/Scroll_boundary\">Scroll boundary</a></li><li><a href=\"/en-US/docs/Glossary/Scroll_chaining\">Scroll chaining</a></li><li><a href=\"/en-US/docs/Glossary/Scroll_container\">Scroll container</a></li><li><a href=\"/en-US/docs/Glossary/Scroll_snap\">Scroll snap</a></li><li><a href=\"/en-US/docs/Glossary/SCTP\">SCTP</a></li><li><a href=\"/en-US/docs/Glossary/SDK\">SDK (Software Development Kit)</a></li><li><a href=\"/en-US/docs/Glossary/SDP\">SDP</a></li><li><a href=\"/en-US/docs/Glossary/Search_engine\">Search engine</a></li><li><a href=\"/en-US/docs/Glossary/Secure_Context\">Secure Context</a></li><li><a href=\"/en-US/docs/Glossary/SSL\">Secure Sockets Layer (SSL)</a></li><li><a href=\"/en-US/docs/Glossary/CSS_Selector\">Selector (CSS)</a></li><li><a href=\"/en-US/docs/Glossary/Self-Executing_Anonymous_Function\">Self-Executing Anonymous Function</a></li><li><a href=\"/en-US/docs/Glossary/Semantics\">Semantics</a></li><li><a href=\"/en-US/docs/Glossary/SEO\">SEO</a></li><li><a href=\"/en-US/docs/Glossary/Serializable_object\">Serializable object</a></li><li><a href=\"/en-US/docs/Glossary/Serialization\">Serialization</a></li><li><a href=\"/en-US/docs/Glossary/Server\">Server</a></li><li><a href=\"/en-US/docs/Glossary/Server_Timing\">Server Timing</a></li><li><a href=\"/en-US/docs/Glossary/Session_Hijacking\">Session Hijacking</a></li><li><a href=\"/en-US/docs/Glossary/SGML\">SGML</a></li><li><a href=\"/en-US/docs/Glossary/Shadow_tree\">Shadow tree</a></li><li><a href=\"/en-US/docs/Glossary/Shallow_copy\">Shallow copy</a></li><li><a href=\"/en-US/docs/Glossary/Shim\">Shim</a></li><li><a href=\"/en-US/docs/Glossary/Signature\">Signature</a></li><li><a href=\"/en-US/docs/Glossary/SIMD\">SIMD</a></li><li><a href=\"/en-US/docs/Glossary/SISD\">SISD</a></li><li><a href=\"/en-US/docs/Glossary/Site\">Site</a></li><li><a href=\"/en-US/docs/Glossary/Site_map\">Site map</a></li><li><a href=\"/en-US/docs/Glossary/SLD\">SLD</a></li><li><a href=\"/en-US/docs/Glossary/Sloppy_mode\">Sloppy mode</a></li><li><a href=\"/en-US/docs/Glossary/Slug\">Slug</a></li><li><a href=\"/en-US/docs/Glossary/Smoke_Test\">Smoke Test</a></li><li><a href=\"/en-US/docs/Glossary/SMPTE\">SMPTE (Society of Motion Picture and Television Engineers)</a></li><li><a href=\"/en-US/docs/Glossary/SMTP\">SMTP</a></li><li><a href=\"/en-US/docs/Glossary/Snake_case\">Snake case</a></li><li><a href=\"/en-US/docs/Glossary/Snap_positions\">Snap positions</a></li><li><a href=\"/en-US/docs/Glossary/SOAP\">SOAP</a></li><li><a href=\"/en-US/docs/Glossary/SPA\">SPA (Single-page application)</a></li><li><a href=\"/en-US/docs/Glossary/Specification\">Specification</a></li><li><a href=\"/en-US/docs/Glossary/Speculative_parsing\">Speculative parsing</a></li><li><a href=\"/en-US/docs/Glossary/Speed_index\">Speed index</a></li><li><a href=\"/en-US/docs/Glossary/SQL\">SQL</a></li><li><a href=\"/en-US/docs/Glossary/SQL_Injection\">SQL Injection</a></li><li><a href=\"/en-US/docs/Glossary/SRI\">SRI</a></li><li><a href=\"/en-US/docs/Glossary/Stacking_context\">Stacking context</a></li><li><a href=\"/en-US/docs/Glossary/State_machine\">State machine</a></li><li><a href=\"/en-US/docs/Glossary/Statement\">Statement</a></li><li><a href=\"/en-US/docs/Glossary/Static_method\">Static method</a></li><li><a href=\"/en-US/docs/Glossary/SSG\">Static site generator (SSG)</a></li><li><a href=\"/en-US/docs/Glossary/Static_typing\">Static typing</a></li><li><a href=\"/en-US/docs/Glossary/Sticky_activation\">Sticky activation</a></li><li><a href=\"/en-US/docs/Glossary/Strict_mode\">Strict mode</a></li><li><a href=\"/en-US/docs/Glossary/String\">String</a></li><li><a href=\"/en-US/docs/Glossary/Stringifier\">Stringifier</a></li><li><a href=\"/en-US/docs/Glossary/STUN\">STUN</a></li><li><a href=\"/en-US/docs/Glossary/Style_origin\">Style origin</a></li><li><a href=\"/en-US/docs/Glossary/Stylesheet\">Stylesheet</a></li><li><a href=\"/en-US/docs/Glossary/Submit_button\">Submit button</a></li><li><a href=\"/en-US/docs/Glossary/SVG\">SVG</a></li><li><a href=\"/en-US/docs/Glossary/SVN\">SVN</a></li><li><a href=\"/en-US/docs/Glossary/Symbol\">Symbol</a></li><li><a href=\"/en-US/docs/Glossary/Symmetric-key_cryptography\">Symmetric-key cryptography</a></li><li><a href=\"/en-US/docs/Glossary/Synchronous\">Synchronous</a></li><li><a href=\"/en-US/docs/Glossary/Syntax\">Syntax</a></li><li><a href=\"/en-US/docs/Glossary/Syntax_error\">Syntax error</a></li><li><a href=\"/en-US/docs/Glossary/Synthetic_monitoring\">Synthetic monitoring</a></li><li><a href=\"/en-US/docs/Glossary/Table_Grid_Box\">Table grid box</a></li><li><a href=\"/en-US/docs/Glossary/Table_Wrapper_Box\">Table Wrapper Box</a></li><li><a href=\"/en-US/docs/Glossary/Tag\">Tag</a></li><li><a href=\"/en-US/docs/Glossary/TCP\">TCP</a></li><li><a href=\"/en-US/docs/Glossary/TCP_handshake\">TCP handshake</a></li><li><a href=\"/en-US/docs/Glossary/TCP_slow_start\">TCP slow start</a></li><li><a href=\"/en-US/docs/Glossary/Telnet\">Telnet</a></li><li><a href=\"/en-US/docs/Glossary/Texel\">Texel</a></li><li><a href=\"/en-US/docs/Glossary/Khronos\">The Khronos Group</a></li><li><a href=\"/en-US/docs/Glossary/Thread\">Thread</a></li><li><a href=\"/en-US/docs/Glossary/Three_js\">Three js</a></li><li><a href=\"/en-US/docs/Glossary/Throttle\">Throttle</a></li><li><a href=\"/en-US/docs/Glossary/Time_to_first_byte\">Time to first byte</a></li><li><a href=\"/en-US/docs/Glossary/Time_to_interactive\">Time to interactive</a></li><li><a href=\"/en-US/docs/Glossary/TLD\">TLD</a></li><li><a href=\"/en-US/docs/Glossary/TOFU\">TOFU</a></li><li><a href=\"/en-US/docs/Glossary/Top_layer\">Top layer</a></li><li><a href=\"/en-US/docs/Glossary/Transient_activation\">Transient activation</a></li><li><a href=\"/en-US/docs/Glossary/TLS\">Transport Layer Security (TLS)</a></li><li><a href=\"/en-US/docs/Glossary/Tree_shaking\">Tree shaking</a></li><li><a href=\"/en-US/docs/Glossary/Trident\">Trident</a></li><li><a href=\"/en-US/docs/Glossary/Truthy\">Truthy</a></li><li><a href=\"/en-US/docs/Glossary/TTL\">TTL</a></li><li><a href=\"/en-US/docs/Glossary/TURN\">TURN</a></li><li><a href=\"/en-US/docs/Glossary/Type\">Type</a></li><li><a href=\"/en-US/docs/Glossary/Type_coercion\">Type coercion</a></li><li><a href=\"/en-US/docs/Glossary/Type_Conversion\">Type conversion</a></li><li><a href=\"/en-US/docs/Glossary/TypeScript\">TypeScript</a></li><li><a href=\"/en-US/docs/Glossary/UAAG\">UAAG</a></li><li><a href=\"/en-US/docs/Glossary/UDP\">UDP (User Datagram Protocol)</a></li><li><a href=\"/en-US/docs/Glossary/UI\">UI</a></li><li><a href=\"/en-US/docs/Glossary/Undefined\">Undefined</a></li><li><a href=\"/en-US/docs/Glossary/Unicode\">Unicode</a></li><li><a href=\"/en-US/docs/Glossary/Unix_time\">Unix time</a></li><li><a href=\"/en-US/docs/Glossary/URI\">URI</a></li><li><a href=\"/en-US/docs/Glossary/URL\">URL</a></li><li><a href=\"/en-US/docs/Glossary/URN\">URN</a></li><li><a href=\"/en-US/docs/Glossary/Usenet\">Usenet</a></li><li><a href=\"/en-US/docs/Glossary/User_agent\">User agent</a></li><li><a href=\"/en-US/docs/Glossary/UTF-8\">UTF-8</a></li><li><a href=\"/en-US/docs/Glossary/UUID\">UUID</a></li><li><a href=\"/en-US/docs/Glossary/UX\">UX</a></li><li><a href=\"/en-US/docs/Glossary/Validator\">Validator</a></li><li><a href=\"/en-US/docs/Glossary/Value\">Value</a></li><li><a href=\"/en-US/docs/Glossary/Variable\">Variable</a></li><li><a href=\"/en-US/docs/Glossary/Vendor_Prefix\">Vendor Prefix</a></li><li><a href=\"/en-US/docs/Glossary/Viewport\">Viewport</a></li><li><a href=\"/en-US/docs/Glossary/Visual_Viewport\">Visual Viewport</a></li><li><a href=\"/en-US/docs/Glossary/Void_element\">Void element</a></li><li><a href=\"/en-US/docs/Glossary/VoIP\">VoIP</a></li><li><a href=\"/en-US/docs/Glossary/W3C\">W3C</a></li><li><a href=\"/en-US/docs/Glossary/WAI\">WAI</a></li><li><a href=\"/en-US/docs/Glossary/WCAG\">WCAG</a></li><li><a href=\"/en-US/docs/Glossary/Web_performance\">Web performance</a></li><li><a href=\"/en-US/docs/Glossary/Web_server\">Web server</a></li><li><a href=\"/en-US/docs/Glossary/Web_standards\">Web standards</a></li><li><a href=\"/en-US/docs/Glossary/WebAssembly\">WebAssembly</a></li><li><a href=\"/en-US/docs/Glossary/WebDAV\">WebDAV</a></li><li><a href=\"/en-US/docs/Glossary/WebExtensions\">WebExtensions</a></li><li><a href=\"/en-US/docs/Glossary/WebGL\">WebGL</a></li><li><a href=\"/en-US/docs/Glossary/WebIDL\">WebIDL</a></li><li><a href=\"/en-US/docs/Glossary/WebKit\">WebKit</a></li><li><a href=\"/en-US/docs/Glossary/WebM\">WebM</a></li><li><a href=\"/en-US/docs/Glossary/WebP\">WebP</a></li><li><a href=\"/en-US/docs/Glossary/WebRTC\">WebRTC</a></li><li><a href=\"/en-US/docs/Glossary/WebSockets\">WebSockets</a></li><li><a href=\"/en-US/docs/Glossary/WebVTT\">WebVTT</a></li><li><a href=\"/en-US/docs/Glossary/WHATWG\">WHATWG</a></li><li><a href=\"/en-US/docs/Glossary/Whitespace\">Whitespace</a></li><li><a href=\"/en-US/docs/Glossary/WindowProxy\">WindowProxy</a></li><li><a href=\"/en-US/docs/Glossary/World_Wide_Web\">World Wide Web</a></li><li><a href=\"/en-US/docs/Glossary/Wrapper\">Wrapper</a></li><li><a href=\"/en-US/docs/Glossary/XForms\">XForms</a><abbr class=\"icon icon-deprecated\" title=\"Deprecated. Not for use in new websites.\">\n <span class=\"visually-hidden\">Deprecated</span>\n</abbr></li><li><a href=\"/en-US/docs/Glossary/XHTML\">XHTML</a></li><li><a href=\"/en-US/docs/Glossary/XInclude\">XInclude</a></li><li><a href=\"/en-US/docs/Glossary/XLink\">XLink</a></li><li><a href=\"/en-US/docs/Glossary/XML\">XML</a></li><li><a href=\"/en-US/docs/Glossary/XMLHttpRequest\">XMLHttpRequest (XHR)</a></li><li><a href=\"/en-US/docs/Glossary/XPath\">XPath</a></li><li><a href=\"/en-US/docs/Glossary/XQuery\">XQuery</a></li><li><a href=\"/en-US/docs/Glossary/XSLT\">XSLT</a></li><li><a href=\"/en-US/docs/Glossary/Zstandard_compression\">Zstandard compression</a></li></ol>\n </li>\n </ol>\n","sidebarMacro":"GlossarySidebar","body":[{"type":"prose","value":{"id":null,"title":null,"isH3":false,"content":"<p>A <strong>function</strong> is a code snippet that can be called by other code or by itself, or a <a href=\"/en-US/docs/Glossary/Variable\">variable</a> that refers to the function. When a function is called, <a href=\"/en-US/docs/Glossary/Argument\">arguments</a> are passed to the function as input, and the function can optionally return a value. A function in <a href=\"/en-US/docs/Glossary/JavaScript\">JavaScript</a> is also an <a href=\"/en-US/docs/Glossary/Object\">object</a>.</p>\n<p>A function name is an <a href=\"/en-US/docs/Glossary/Identifier\">identifier</a> included as part of a function declaration or function expression. The function name's <a href=\"/en-US/docs/Glossary/Scope\">scope</a> depends on whether the function name is a declaration or expression.</p>"}},{"type":"prose","value":{"id":"different_types_of_functions","title":"Different types of functions","isH3":true,"content":"<p>An <strong>anonymous function</strong> is a function without a function name. Only function expressions can be anonymous, function declarations must have a name:</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">js</span></div><pre class=\"brush: js notranslate\"><code>// Anonymous function created as a function expression\n(function () {});\n\n// Anonymous function created as an arrow function\n() => {};\n</code></pre></div>\n<p>The following terms are not used in the ECMAScript language specification, they're jargon used to refer to different types of functions.</p>\n<p>A <strong>named function</strong> is a function with a function name:</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">js</span></div><pre class=\"brush: js notranslate\"><code>// Function declaration\nfunction foo() {}\n\n// Named function expression\n(function bar() {});\n\n// Arrow function\nconst baz = () => {};\n</code></pre></div>\n<p>An <strong>inner function</strong> is a function inside another function (<code>square</code> in this case). An <strong>outer function</strong> is a function containing a function (<code>addSquares</code> in this case):</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">js</span></div><pre class=\"brush: js notranslate\"><code>function addSquares(a, b) {\n function square(x) {\n return x * x;\n }\n return square(a) + square(b);\n}\n\n// Arrow function\nconst addSquares2 = (a, b) => {\n const square = (x) => x * x;\n return square(a) + square(b);\n};\n</code></pre></div>\n<p>A <strong>recursive function</strong> is a function that calls itself. See <a href=\"/en-US/docs/Glossary/Recursion\">recursion</a>.</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">js</span></div><pre class=\"brush: js notranslate\"><code>function loop(x) {\n if (x >= 10) return;\n loop(x + 1);\n}\n\n// Arrow function\nconst loop2 = (x) => {\n if (x >= 10) return;\n loop(x + 1);\n};\n</code></pre></div>\n<p>An <strong>Immediately Invoked Function Expression</strong> (<a href=\"/en-US/docs/Glossary/IIFE\">IIFE</a>) is a function that is called directly after the function is loaded into the browser's compiler. The way to identify an IIFE is by locating the extra left and right parenthesis at the end of the function's definition.</p>\n<p>Function expressions, named or anonymous, can be called immediately.</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">js</span></div><pre class=\"brush: js notranslate\"><code>(function foo() {\n console.log(\"Hello Foo\");\n})();\n\n(function food() {\n console.log(\"Hello Food\");\n})();\n\n(() => console.log(\"hello world\"))();\n</code></pre></div>\n<p>Declared functions can't be called immediately this way, because IIFEs must be function <em>expressions</em>.</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">js</span></div><pre class=\"brush: js example-bad notranslate\"><code>function foo() {\n console.log('Hello Foo');\n}();\n</code></pre></div>\n<p>If you'd like to know more about IIFEs, check out the following page on Wikipedia: <a href=\"https://en.wikipedia.org/wiki/Immediately_invoked_function_expression\" class=\"external\" target=\"_blank\">Immediately Invoked Function Expression</a></p>"}},{"type":"prose","value":{"id":"see_also","title":"See also","isH3":false,"content":"<ul>\n <li><a href=\"/en-US/docs/Web/JavaScript/Guide/Functions\">Functions</a></li>\n <li><a href=\"/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions\">Arrow Functions</a></li>\n</ul>"}}],"toc":[{"text":"See also","id":"see_also"}],"summary":"A function is a code snippet that can be called by other code or by itself, or a variable that refers to the function. When a function is called, arguments are passed to the function as input, and the function can optionally return a value. A function in JavaScript is also an object.","popularity":0,"modified":"2023-10-17T14:05:16.000Z","other_translations":[{"locale":"de","title":"Function","native":"Deutsch"},{"locale":"es","title":"Función","native":"Español"},{"locale":"fr","title":"Fonction","native":"Français"},{"locale":"ja","title":"Function (関数)","native":"日本語"},{"locale":"ko","title":"함수 (function)","native":"한국어"},{"locale":"pt-BR","title":"Função","native":"Português (do Brasil)"},{"locale":"ru","title":"Функция","native":"Русский"},{"locale":"zh-CN","title":"Function（函数）","native":"中文 (简体)"}],"pageType":"glossary-definition","source":{"folder":"en-us/glossary/function","github_url":"https://github.com/mdn/content/blob/main/files/en-us/glossary/function/index.md","last_commit_url":"https://github.com/mdn/content/commit/07fd308d45223fc5792d6dc13e3ab2c8826e1b44","filename":"index.md"},"short_title":"Function","parents":[{"uri":"/en-US/docs/Glossary","title":"Glossary"},{"uri":"/en-US/docs/Glossary/Function","title":"Function"}],"pageTitle":"Function - MDN Web Docs Glossary: Definitions of Web-related terms | MDN","noIndexing":false}}</script></body></html>