JavaScript For Loop

<!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <meta name="viewport" content="width=device-width, initial-scale=1"> <meta name="keywords" content="javascript for loop, while, if, case, else, for, javascript tutorial, code, function, source, learn, method, javascript dropdown menu, jscript, reference"> <meta name="Description" content="Learn about the JavaScript For Loop"> <link rel="canonical" href="https://www.quackit.com/javascript/tutorial/javascript_for_loop.cfm"> <title>JavaScript For Loop</title> <script src="//ajax.googleapis.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script> <link rel="shortcut icon" href="/pix/favicon96.png"> <link rel="apple-touch-icon" href="/pix/apple-touch-icon.png"> <link rel="preconnect" href="https://fonts.googleapis.com"> <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin> <link href="https://fonts.googleapis.com/css2?family=Lato:ital,wght@0,400;0,700;1,400&display=swap" rel="stylesheet"> <link href="/common/css/master.45.min.css" rel="stylesheet"> <script async src="https://cdn.fuseplatform.net/publift/tags/2/3499/fuse.js"></script>  <script async src="https://www.googletagmanager.com/gtag/js?id=G-Q3H025ZKLN"></script> <script> window.dataLayer = window.dataLayer || []; function gtag(){dataLayer.push(arguments);} gtag('js', new Date()); gtag('config', 'G-Q3H025ZKLN'); </script> </head> <body> <header class="site-header"> <div class="site-header-base"> <div class="site-logo"> <a title="Quackit Homepage" target="_top" href="/"><img src="/pix/quackit_logo_watermark.png" width="87" height="33" alt="Quackit Logo"></a> </div> <button id="site-nav-toggler" class="site-nav-toggler" aria-expanded="false" aria-controls="site-nav"> <span class="sr-only">Toggle navigation</span> ☰ </button> </div> <nav id="site-nav" class="site-nav"> <div class="site-links"> <ul> <li><a href="/"><i class="fa fa-home"></i> <span class="sr-only">Home</span></a></li> <li><a href="/html/">HTML</a></li> <li><a href="/css/">CSS</a></li> <li><a href="/scripting/">Scripting</a></li> <li><a href="/database/">Database</a></li> </ul> </div> <div class="site-search-top"> <form action="/search/" id="cse-search-box-bottom" class="site-search"> <div> <input type="hidden" name="cx" value="partner-pub-6331358926293806:98x0fk-bbgi"> <input type="hidden" name="cof" value="FORID:10"> <input type="hidden" name="ie" value="ISO-8859-1"> <input type="text" name="q" size="20" class="site-search-input"> <button type="submit" name="sa" class="site-search-button"><i class="fa fa-search"></i></button> </div> </form> </div> </nav> </header> <div class="main"> <article class="content"> <h1 class="page-title">JavaScript For Loop</h1> <div class="ad ad-top">  <div data-fuse="23059883623"></div> </div> <ul class="pager"> <li><a href="/javascript/tutorial/javascript_while_loop.cfm"><i class="fa fa-long-arrow-left" aria-hidden="true"></i> While Loops</a></li> <li><a href="/javascript/tutorial/javascript_try_catch.cfm">JavaScript Try/Catch <i class="fa fa-long-arrow-right" aria-hidden="true"></i></a></li> </ul> <p class="lead">This page explains the "for" loop, and why it's different to the "while" loop.</p> <p>We learned in the previous lesson that "loops" enable your program to continuously execute a block of code for a given number of times, or while a given condition is true.</p> <p>In that lesson, we saw that the While loop executes code <em>while</em> a condition is true.</p> <p>In this lesson, we will see that the JavaScript For loop executes code <em>for</em> a specified number of times. </p> <p>Therefore, we could rewrite the example from the previous lesson to use a for loop.</p> <div class="ad">  <div data-fuse="23059883629"></div> </div> <h2>Example For statement:</h2> <script src="/common/js/codemirror/lib/codemirror.js"></script> <script src="/common/js/codemirror/mode/htmlmixed/htmlmixed.js"></script> <script src="/common/js/codemirror/mode/css/css.js"></script> <script src="/common/js/codemirror/mode/javascript/javascript.js"></script> <script src="/common/js/codemirror/mode/xml/xml.js"></script> <div class="code-only"> <textarea id="example1" autocomplete="off" spellcheck="false"><script>
var myBankBalance = 0;
var msg = "";
for (myBankBalance = 0; myBankBalance <= 10; myBankBalance++) {
 msg = msg + "My bank balance is $" + myBankBalance + "<br>";
}
document.write(msg);
</script></textarea> </div> <script> var exampleCode1 = CodeMirror.fromTextArea(document.getElementById("example1"), { mode: "htmlmixed", tabMode: "indent", styleActiveLine: false, lineNumbers: false, lineWrapping: true, theme: "q-dark" }); </script> <h3>Exlanation of code</h3> <ol> <li><p>We started by declaring a variable called <var>myBankBalance</var> and setting it to <samp>0</samp>.</p></li> <li><p>We then opened a for loop with our condition between brackets.</p> <p>Our condition sets a value to our variable, checks if the current value of the variable is less than or equal to 10, then increments the value by 1. </p></li> <li><p>This is followed by code to execute while the condition is true.</p> <p>In this case, we are simply, outputting the current value of <var>myBankBalance</var>, preceded by some text. This code is placed within curly braces. </p> </li> <li><p>When the browser reaches the closing curly brace, if the condition is still true, it goes back to the first curly brace and executes the code again.</p> <p>Of course, by now, the <var>myBankBalance</var> variable has been incremented by 1. If the condition is not true (i.e. the variable is greater than 10), it exits from the loop.</p></li> </ol> <ul class="pager"> <li><a href="/javascript/tutorial/javascript_while_loop.cfm"><i class="fa fa-long-arrow-left" aria-hidden="true"></i> While Loops</a></li> <li><a href="/javascript/tutorial/javascript_try_catch.cfm">JavaScript Try/Catch <i class="fa fa-long-arrow-right" aria-hidden="true"></i></a></li> </ul> </article> <div class="sidebar"> <nav> <ul> <li> <h3><a href="/javascript/tutorial/">JavaScript Tutorial</a></h3> <ul> <li><a href="/javascript/tutorial/introduction.cfm">Introduction</a></li> <li><a href="/javascript/tutorial/how_to_enable_javascript.cfm">How to Enable JavaScript</a></li> <li><a href="/javascript/tutorial/javascript_syntax.cfm">JavaScript Syntax</a></li> <li><a href="/javascript/tutorial/javascript_popup_boxes.cfm">JavaScript Popup Boxes</a></li> <li><a href="/javascript/tutorial/javascript_html.cfm">JavaScript and HTML</a></li> <li><a href="/javascript/tutorial/external_javascript_file.cfm">External JavaScript File</a></li> <li><a href="/javascript/tutorial/javascript_operators.cfm">JavaScript Operators</a></li> <li><a href="/javascript/tutorial/javascript_variables.cfm">JavaScript Variables</a></li> <li><a href="/javascript/tutorial/javascript_functions.cfm">JavaScript Functions</a></li> <li><a href="/javascript/tutorial/javascript_events.cfm">JavaScript Events</a></li> <li><a href="/javascript/tutorial/javascript_if_statements.cfm">JavaScript If Statements</a></li> <li><a href="/javascript/tutorial/javascript_switch_statement.cfm">JavaScript Switch Statements</a></li> <li><a href="/javascript/tutorial/javascript_while_loop.cfm">JavaScript While Loop</a></li> <li><a href="/javascript/tutorial/javascript_for_loop.cfm">JavaScript For Loop</a></li> <li><a href="/javascript/tutorial/javascript_try_catch.cfm">JavaScript Try Catch</a></li> <li><a href="/javascript/tutorial/javascript_escape_characters.cfm">JavaScript Escape Characters</a></li> <li><a href="/javascript/tutorial/javascript_void_0.cfm">JavaScript Void(0)</a></li> <li><a href="/javascript/tutorial/javascript_cookies.cfm">JavaScript Cookies</a></li> <li><a href="/javascript/tutorial/javascript_date_and_time.cfm">JavaScript Date and Time</a></li> <li><a href="/javascript/tutorial/javascript_arrays.cfm">JavaScript Arrays</a></li> <li><a href="/javascript/tutorial/two_dimensional_arrays.cfm">Two Dimensional Arrays</a></li> <li><a href="/javascript/tutorial/innerhtml_in_javascript.cfm">JavaScript innerHTML</a></li> <li><a href="/javascript/tutorial/unobtrusive_javascript.cfm">Unobtrusive JavaScript</a></li> <li><a href="/javascript/tutorial/javascript_summary.cfm">JavaScript Summary</a></li> </ul> </li> <li><h3>JavaScript Reference</h3> <ul> <li><a href="/javascript/examples/" title="">JavaScript Examples</a></li> <li><a href="/javascript/javascript_reserved_words.cfm" title="">JavaScript Reserved Words</a></li> <li><a href="/javascript/javascript_event_handlers.cfm" title="Introduction to the 12 JavaScript event handlers">JavaScript Event Handlers</a></li> <li><a href="/javascript/javascript_date_and_time_functions.cfm" title="Full listing of all JavaScript methods for dealing with date and time.">JavaScript Date and Time Functions</a></li> </ul> <li><h3>jQuery</h3> <ul> <li><a href="/jquery/tutorial/" title="">jQuery Tutorial</a></li> <li><a href="/jquery/examples/" title="">jQuery Examples</a></li> </ul> </li> <li><h3>JSON</h3> <ul> <li><a href="/json/tutorial/" title="Data format for exchanging data between applications and different environments.">JSON Tutorial</a></li> </ul> <li> </ul> </nav> <div class="ad ad-left">  <div data-fuse="23059511712"></div> </div> </div> <div class="ads"> <div class="ad ad-right">  <div data-fuse="23059883626"></div> </div> </div> </div> <div class="searchbox-bottom"> <form action="/search/" id="cse-search-box-bottom" class="site-search"> <div> <input type="hidden" name="cx" value="partner-pub-6331358926293806:npmuvy-i8kk"> <input type="hidden" name="cof" value="FORID:10"> <input type="hidden" name="ie" value="ISO-8859-1"> <input type="text" name="q" size="30" class="site-search-input"> <button type="submit" name="sa" class="site-search-button"><i class="fa fa-search"></i></button> </div> </form> <script src="//cse.google.com/cse/brand?form=cse-search-box-bottom&lang=en"></script> </div> <footer> <p class="about"><a href="/"><i class="fa fa-home"></i> Home</a> | <a href="/about.cfm" rel="nofollow">About</a> | <a href="/contact.cfm" rel="nofollow">Contact</a> | <a href="/terms_of_use.cfm" rel="nofollow">Terms of Use</a> | <a href="/privacy_policy.cfm" rel="nofollow">Privacy Policy</a></p> <p>© Copyright 2000 - 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JavaScript For Loop