CSS Custom Highlight API - Web APIs

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href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/CSS_Custom_Highlight_API?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB#browser_compatibility">Browser compatibility</a></li> <li class="document-toc-item "><a class="document-toc-link" href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/CSS_Custom_Highlight_API?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB#see_also">See also</a></li> </ul> </section> </div> </div> <div class="sidebar-body"> <ol> <li class="section"><em><a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/CSS_Custom_Highlight_API?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB" aria-current="page">CSS Custom Highlight API</a></em></li> <li class="toggle"> <details open> <summary>Interfaces</summary> <ol> <li><a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/Highlight?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB"><code>Highlight</code></a></li> <li><a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/HighlightRegistry?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB"><code>HighlightRegistry</code></a></li> </ol> </details></li> <li class="toggle"> <details open> <summary>Properties</summary> <ol> <li><a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/CSS/highlights_static?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB"><code>CSS.highlights_static</code></a></li> </ol> </details></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="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/CSS_Custom_Highlight_API?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB#concepts_and_usage">Concepts and usage</a></li> <li class="document-toc-item "><a class="document-toc-link" href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/CSS_Custom_Highlight_API?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB#interfaces">Interfaces</a></li> <li class="document-toc-item "><a class="document-toc-link" href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/CSS_Custom_Highlight_API?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB#examples">Examples</a></li> <li class="document-toc-item "><a class="document-toc-link" href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/CSS_Custom_Highlight_API?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB#specifications">Specifications</a></li> <li class="document-toc-item "><a class="document-toc-link" href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/CSS_Custom_Highlight_API?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB#browser_compatibility">Browser compatibility</a></li> <li class="document-toc-item "><a class="document-toc-link" href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/CSS_Custom_Highlight_API?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB#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>CSS Custom Highlight API</h1> </header> <div class="section-content"> <p>The CSS Custom Highlight API provides a mechanism for styling arbitrary text ranges on a document by using JavaScript to create the ranges, and CSS to style them.</p> </div> <section aria-labelledby="concepts_and_usage"> <h2 id="concepts_and_usage"><a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/CSS_Custom_Highlight_API?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB#concepts_and_usage">Concepts and usage</a></h2> <div class="section-content"> <p>Styling text ranges on a webpage can be very useful. For example, text editing web apps highlight spelling or grammar errors, and code editors highlight syntax errors.</p> <p>The CSS Custom Highlight API extends the concept of other highlight pseudo-elements such as <a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/CSS/::selection?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB"><code>::selection</code></a>, <a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/CSS/::spelling-error?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB"><code>::spelling-error</code></a>, <a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/CSS/::grammar-error?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB"><code>::grammar-error</code></a>, and <a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/CSS/::target-text?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB"><code>::target-text</code></a> by providing a way to create and style arbitrary <a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/Range?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB"><code>Range</code></a> objects, rather than being limited to browser-defined ranges.</p> <p>Using the CSS Custom Highlight API, you can programmatically create text ranges and highlight them without affecting the DOM structure in the page.</p> <p>There are four steps to style text ranges on a webpage using the CSS Custom Highlight API:</p> <ol> <li>Creating <a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/Range?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB"><code>Range</code></a> objects.</li> <li>Creating <a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/Highlight?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB"><code>Highlight</code></a> objects for these ranges.</li> <li>Registering the highlights using the <a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/HighlightRegistry?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB"><code>HighlightRegistry</code></a>.</li> <li>Styling the highlights using the <a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/CSS/::highlight?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB"><code>::highlight()</code></a> pseudo-element.</li> </ol> </div> </section> <section aria-labelledby="create_ranges"> <h3 id="create_ranges"><a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/CSS_Custom_Highlight_API?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB#create_ranges">Create ranges</a></h3> <div class="section-content"> <p>The first step is to define the text ranges that you want to style by creating <a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/Range?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB"><code>Range</code></a> objects in JavaScript. For example:</p> <div class="code-example"> <div class="example-header"> <span class="language-name">js</span> </div> <pre class="brush: js notranslate"><code>const parentNode = document.getElementById("foo"); const range1 = new Range(); range1.setStart(parentNode, 10); range1.setEnd(parentNode, 20); const range2 = new Range(); range2.setStart(parentNode, 40); range2.setEnd(parentNode, 60); </code></pre> </div> </div> </section> <section aria-labelledby="create_highlights"> <h3 id="create_highlights"><a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/CSS_Custom_Highlight_API?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB#create_highlights">Create highlights</a></h3> <div class="section-content"> <p>The second step is to instantiate <a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/Highlight?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB"><code>Highlight</code></a> objects for your text ranges.</p> <p>Multiple ranges can be associated to one highlight. If you want to highlight multiple pieces of text the same way, you need to create a single highlight and initialize it with the corresponding ranges.</p> <div class="code-example"> <div class="example-header"> <span class="language-name">js</span> </div> <pre class="brush: js notranslate"><code>const highlight = new Highlight(range1, range2); </code></pre> </div> <p>But you can also create as many highlights as you need. For example, if you are building a collaborative text editor where each user gets a different text color, then you can create one highlight per user, as seen in the code snippet below:</p> <div class="code-example"> <div class="example-header"> <span class="language-name">js</span> </div> <pre class="brush: js notranslate"><code>const user1Highlight = new Highlight(user1Range1, user1Range2); const user2Highlight = new Highlight(user2Range1, user2Range2, user2Range3); </code></pre> </div> <p>Each highlight can be styled differently.</p> </div> </section> <section aria-labelledby="register_highlights"> <h3 id="register_highlights"><a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/CSS_Custom_Highlight_API?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB#register_highlights">Register highlights</a></h3> <div class="section-content"> <p>Once highlights have been created, register them by using the <a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/HighlightRegistry?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB"><code>HighlightRegistry</code></a> available as <a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/CSS/highlights_static?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB" title="CSS.highlights"><code>CSS.highlights</code></a>.</p> <p>The registry is a <a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB"><code>Map</code></a>-like object used to register highlights by names, as seen below:</p> <div class="code-example"> <div class="example-header"> <span class="language-name">js</span> </div> <pre class="brush: js notranslate"><code>CSS.highlights.set("user-1-highlight", user1Highlight); CSS.highlights.set("user-2-highlight", user2Highlight); </code></pre> </div> <p>In the above code snippet, the <code>user-1-highlight</code> and <code>user-2-highlight</code> strings are custom identifiers that can be used in CSS to apply styles to the registered highlights.</p> <p>You can register as many highlights as you need in the registry, as well as remove highlights and clear the entire registry.</p> <div class="code-example"> <div class="example-header"> <span class="language-name">js</span> </div> <pre class="brush: js notranslate"><code>// Remove a single highlight from the registry. CSS.highlights.delete("user-1-highlight"); // Clear the registry. CSS.highlights.clear(); </code></pre> </div> </div> </section> <section aria-labelledby="style_highlights"> <h3 id="style_highlights"><a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/CSS_Custom_Highlight_API?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB#style_highlights">Style highlights</a></h3> <div class="section-content"> <p>The final step is to style the registered highlights. This is done by using the <a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/CSS/::highlight?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB"><code>::highlight()</code></a> pseudo-element. For example, to style the <code>user-1-highlight</code> highlight registered in the previous step:</p> <div class="code-example"> <div class="example-header"> <span class="language-name">css</span> </div> <pre class="brush: css notranslate"><code>::highlight(user-1-highlight) { background-color: yellow; color: black; } </code></pre> </div> </div> </section> <section aria-labelledby="interfaces"> <h2 id="interfaces"><a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/CSS_Custom_Highlight_API?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB#interfaces">Interfaces</a></h2> <div class="section-content"> <dl> <dt id="highlight"> <a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/Highlight?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB"><code>Highlight</code></a> </dt> <dd> <p>This interface is used to represent a collection of ranges to be styled on a document.</p> </dd> <dt id="highlightregistry"> <a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/HighlightRegistry?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB"><code>HighlightRegistry</code></a> </dt> <dd> <p>Accessible via <a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/CSS/highlights_static?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB" title="CSS.highlights"><code>CSS.highlights</code></a>, this <a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB"><code>Map</code></a>-like object is used to register highlights with custom identifiers.</p> </dd> </dl> </div> </section> <section aria-labelledby="examples"> <h2 id="examples"><a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/CSS_Custom_Highlight_API?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB#examples">Examples</a></h2> <div class="section-content"></div> </section> <section aria-labelledby="highlighting_search_results"> <h3 id="highlighting_search_results"><a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/CSS_Custom_Highlight_API?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB#highlighting_search_results">Highlighting search results</a></h3> <div class="section-content"> <p>This example shows how to use the CSS Custom Highlight API to highlight search results.</p> <h4 id="html">HTML</h4> <p>The HTML code snippet below defines a search field and an article with a few paragraphs of text:</p> <div class="code-example"> <div class="example-header"> <span class="language-name">html</span> </div> <pre class="brush: html notranslate"><code><label>Search within text <input id="query" type="text" /></label> <article> <p> Maxime debitis hic, delectus perspiciatis laborum molestiae labore, deleniti, quam consequatur iure veniam alias voluptas nisi quo. Dolorem eaque alias, quo vel quas repudiandae architecto deserunt quidem, sapiente laudantium nulla. </p> <p> Maiores odit molestias, necessitatibus doloremque dolor illum reprehenderit provident nostrum laboriosam iste, tempore perferendis! Ab porro neque esse voluptas libero necessitatibus fugiat, ex, minus atque deserunt veniam molestiae tempora? Vitae. </p> <p> Dolorum facilis voluptate eaque eius similique ducimus dignissimos assumenda quos architecto. Doloremque deleniti non exercitationem rerum quam alias harum, nisi obcaecati corporis temporibus vero sapiente voluptatum est quibusdam id ipsa. </p> </article> </code></pre> </div> <h4 id="javascript">JavaScript</h4> <p>JavaScript is used to listen to the <code>input</code> event on the search field. When the event is fired, the code locates matches for the input text in the article text. It then creates ranges for the matches, and uses the CSS Custom Highlight API to create and register a <code>search-results</code> highlight object:</p> <div class="code-example"> <div class="example-header"> <span class="language-name">js</span> </div> <pre class="brush: js notranslate"><code>const query = document.getElementById("query"); const article = document.querySelector("article"); // Find all text nodes in the article. We'll search within // these text nodes. const treeWalker = document.createTreeWalker(article, NodeFilter.SHOW_TEXT); const allTextNodes = []; let currentNode = treeWalker.nextNode(); while (currentNode) { allTextNodes.push(currentNode); currentNode = treeWalker.nextNode(); } // Listen to the input event to run the search. query.addEventListener("input", () => { // If the CSS Custom Highlight API is not supported, // display a message and bail-out. if (!CSS.highlights) { article.textContent = "CSS Custom Highlight API not supported."; return; } // Clear the HighlightRegistry to remove the // previous search results. CSS.highlights.clear(); // Clean-up the search query and bail-out if // if it's empty. const str = query.value.trim().toLowerCase(); if (!str) { return; } // Iterate over all text nodes and find matches. const ranges = allTextNodes .map((el) => { return { el, text: el.textContent.toLowerCase() }; }) .map(({ text, el }) => { const indices = []; let startPos = 0; while (startPos < text.length) { const index = text.indexOf(str, startPos); if (index === -1) break; indices.push(index); startPos = index + str.length; } // Create a range object for each instance of // str we found in the text node. return indices.map((index) => { const range = new Range(); range.setStart(el, index); range.setEnd(el, index + str.length); return range; }); }); // Create a Highlight object for the ranges. const searchResultsHighlight = new Highlight(...ranges.flat()); // Register the Highlight object in the registry. CSS.highlights.set("search-results", searchResultsHighlight); }); </code></pre> </div> <h4 id="css">CSS</h4> <p>Finally, the <code>::highlight()</code> pseudo-element is used in CSS to style the highlights:</p> <div class="code-example"> <div class="example-header"> <span class="language-name">css</span> </div> <pre class="brush: css notranslate"><code>::highlight(search-results) { background-color: #f06; color: white; } </code></pre> </div> <h4 id="result">Result</h4> <p>The result is shown below. Type text within the search field to highlight matches in the article:</p> <div class="code-example"> <div class="example-header"></div><iframe class="sample-code-frame" title="Highlighting search results sample" id="frame_highlighting_search_results" width="700" height="300" src="about:blank" data-live-path="/en-US/docs/Web/API/CSS_Custom_Highlight_API" data-live-id="highlighting_search_results" sandbox="allow-same-origin allow-scripts" loading="lazy"></iframe> </div> </div> </section> <h2 id="specifications"><a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/CSS_Custom_Highlight_API?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB#specifications">Specifications</a></h2> <table class="standard-table"> <thead> <tr> <th scope="col">Specification</th> </tr> </thead> <tbody> <tr> <td><a href="https://translate.google.com/website?sl=pl&tl=ja&hl=en-GB&u=https://drafts.csswg.org/css-highlight-api-1/">CSS Custom Highlight API Module Level 1 <br></a></td> </tr> </tbody> </table> <section aria-labelledby="browser_compatibility"> <h2 id="browser_compatibility"><a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/CSS_Custom_Highlight_API?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB#browser_compatibility">Browser compatibility</a></h2> <div class="section-content"></div> </section> <h3 id="api.highlight"><a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/CSS_Custom_Highlight_API?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB#api.highlight">api.Highlight</a></h3> <p>BCD tables only load in the browser <noscript>with JavaScript enabled. Enable JavaScript to view data. </noscript></p> <h3 id="api.highlightregistry"><a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/CSS_Custom_Highlight_API?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB#api.highlightregistry">api.HighlightRegistry</a></h3> <p>BCD tables only load in the browser <noscript>with JavaScript enabled. Enable JavaScript to view data. </noscript></p> <h3 id="css.selectors.highlight"><a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/CSS_Custom_Highlight_API?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB#css.selectors.highlight">css.selectors.highlight</a></h3> <p>BCD tables only load in the browser <noscript>with JavaScript enabled. Enable JavaScript to view data. </noscript></p> <section aria-labelledby="see_also"> <h2 id="see_also"><a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/API/CSS_Custom_Highlight_API?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB#see_also">See also</a></h2> <div class="section-content"> <ul> <li><a href="https://translate.google.com/website?sl=pl&tl=ja&hl=en-GB&u=https://css-tricks.com/css-custom-highlight-api-early-look/" class="external" target="_blank">CSS Custom Highlight API: The Future of Highlighting Text Ranges on the Web</a></li> <li>HTML <a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/HTML/Global_attributes/contenteditable?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB"><code>contentEditable</code></a> attribute</li> <li>CSS <a href="https://developer-mozilla-org.translate.goog/en-US/docs/Web/CSS/Pseudo-elements?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB"><code>pseudo-elements</code></a></li> </ul> </div> </section> </article> <aside class="article-footer"> 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Content available under <a href="https://developer-mozilla-org.translate.goog/en-US/docs/MDN/Writing_guidelines/Attrib_copyright_license?_x_tr_sl=pl&_x_tr_tl=ja&_x_tr_hl=en-GB">a Creative Commons license</a>.</p> </div> </div> </footer> </div> <script type="application/json" id="hydration">{"url":"/en-US/docs/Web/API/CSS_Custom_Highlight_API","doc":{"isMarkdown":true,"isTranslated":false,"isActive":true,"flaws":{},"title":"CSS Custom Highlight API","mdn_url":"/en-US/docs/Web/API/CSS_Custom_Highlight_API","locale":"en-US","native":"English (US)","browserCompat":["api.Highlight","api.HighlightRegistry","css.selectors.highlight"],"sidebarHTML":"<ol><li class=\"section\"><em><a href=\"/en-US/docs/Web/API/CSS_Custom_Highlight_API\" aria-current=\"page\">CSS Custom Highlight API</a></em></li><li class=\"toggle\"><details open=\"\"><summary>Interfaces</summary><ol><li><a href=\"/en-US/docs/Web/API/Highlight\"><code>Highlight</code></a></li><li><a href=\"/en-US/docs/Web/API/HighlightRegistry\"><code>HighlightRegistry</code></a></li></ol></details></li><li class=\"toggle\"><details open=\"\"><summary>Properties</summary><ol><li><a href=\"/en-US/docs/Web/API/CSS/highlights_static\"><code>CSS.highlights_static</code></a></li></ol></details></li></ol>","sidebarMacro":"DefaultAPISidebar","body":[{"type":"prose","value":{"id":null,"title":null,"isH3":false,"content":"<p>The CSS Custom Highlight API provides a mechanism for styling arbitrary text ranges on a document by using JavaScript to create the ranges, and CSS to style them.</p>"}},{"type":"prose","value":{"id":"concepts_and_usage","title":"Concepts and usage","isH3":false,"content":"<p>Styling text ranges on a webpage can be very useful. For example, text editing web apps highlight spelling or grammar errors, and code editors highlight syntax errors.</p>\n<p>The CSS Custom Highlight API extends the concept of other highlight pseudo-elements such as <a href=\"/en-US/docs/Web/CSS/::selection\"><code>::selection</code></a>, <a href=\"/en-US/docs/Web/CSS/::spelling-error\"><code>::spelling-error</code></a>, <a href=\"/en-US/docs/Web/CSS/::grammar-error\"><code>::grammar-error</code></a>, and <a href=\"/en-US/docs/Web/CSS/::target-text\"><code>::target-text</code></a> by providing a way to create and style arbitrary <a href=\"/en-US/docs/Web/API/Range\"><code>Range</code></a> objects, rather than being limited to browser-defined ranges.</p>\n<p>Using the CSS Custom Highlight API, you can programmatically create text ranges and highlight them without affecting the DOM structure in the page.</p>\n<p>There are four steps to style text ranges on a webpage using the CSS Custom Highlight API:</p>\n<ol>\n <li>Creating <a href=\"/en-US/docs/Web/API/Range\"><code>Range</code></a> objects.</li>\n <li>Creating <a href=\"/en-US/docs/Web/API/Highlight\"><code>Highlight</code></a> objects for these ranges.</li>\n <li>Registering the highlights using the <a href=\"/en-US/docs/Web/API/HighlightRegistry\"><code>HighlightRegistry</code></a>.</li>\n <li>Styling the highlights using the <a href=\"/en-US/docs/Web/CSS/::highlight\"><code>::highlight()</code></a> pseudo-element.</li>\n</ol>"}},{"type":"prose","value":{"id":"create_ranges","title":"Create ranges","isH3":true,"content":"<p>The first step is to define the text ranges that you want to style by creating <a href=\"/en-US/docs/Web/API/Range\"><code>Range</code></a> objects in JavaScript. For example:</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">js</span></div><pre class=\"brush: js notranslate\"><code>const parentNode = document.getElementById(\"foo\");\n\nconst range1 = new Range();\nrange1.setStart(parentNode, 10);\nrange1.setEnd(parentNode, 20);\n\nconst range2 = new Range();\nrange2.setStart(parentNode, 40);\nrange2.setEnd(parentNode, 60);\n</code></pre></div>"}},{"type":"prose","value":{"id":"create_highlights","title":"Create highlights","isH3":true,"content":"<p>The second step is to instantiate <a href=\"/en-US/docs/Web/API/Highlight\"><code>Highlight</code></a> objects for your text ranges.</p>\n<p>Multiple ranges can be associated to one highlight. If you want to highlight multiple pieces of text the same way, you need to create a single highlight and initialize it with the corresponding ranges.</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">js</span></div><pre class=\"brush: js notranslate\"><code>const highlight = new Highlight(range1, range2);\n</code></pre></div>\n<p>But you can also create as many highlights as you need. For example, if you are building a collaborative text editor where each user gets a different text color, then you can create one highlight per user, as seen in the code snippet below:</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">js</span></div><pre class=\"brush: js notranslate\"><code>const user1Highlight = new Highlight(user1Range1, user1Range2);\nconst user2Highlight = new Highlight(user2Range1, user2Range2, user2Range3);\n</code></pre></div>\n<p>Each highlight can be styled differently.</p>"}},{"type":"prose","value":{"id":"register_highlights","title":"Register highlights","isH3":true,"content":"<p>Once highlights have been created, register them by using the <a href=\"/en-US/docs/Web/API/HighlightRegistry\"><code>HighlightRegistry</code></a> available as <a href=\"/en-US/docs/Web/API/CSS/highlights_static\" title=\"CSS.highlights\"><code>CSS.highlights</code></a>.</p>\n<p>The registry is a <a href=\"/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map\"><code>Map</code></a>-like object used to register highlights by names, as seen below:</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">js</span></div><pre class=\"brush: js notranslate\"><code>CSS.highlights.set(\"user-1-highlight\", user1Highlight);\nCSS.highlights.set(\"user-2-highlight\", user2Highlight);\n</code></pre></div>\n<p>In the above code snippet, the <code>user-1-highlight</code> and <code>user-2-highlight</code> strings are custom identifiers that can be used in CSS to apply styles to the registered highlights.</p>\n<p>You can register as many highlights as you need in the registry, as well as remove highlights and clear the entire registry.</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">js</span></div><pre class=\"brush: js notranslate\"><code>// Remove a single highlight from the registry.\nCSS.highlights.delete(\"user-1-highlight\");\n\n// Clear the registry.\nCSS.highlights.clear();\n</code></pre></div>"}},{"type":"prose","value":{"id":"style_highlights","title":"Style highlights","isH3":true,"content":"<p>The final step is to style the registered highlights. This is done by using the <a href=\"/en-US/docs/Web/CSS/::highlight\"><code>::highlight()</code></a> pseudo-element. For example, to style the <code>user-1-highlight</code> highlight registered in the previous step:</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">css</span></div><pre class=\"brush: css notranslate\"><code>::highlight(user-1-highlight) {\n background-color: yellow;\n color: black;\n}\n</code></pre></div>"}},{"type":"prose","value":{"id":"interfaces","title":"Interfaces","isH3":false,"content":"<dl>\n <dt id=\"highlight\"><a href=\"/en-US/docs/Web/API/Highlight\"><code>Highlight</code></a></dt>\n <dd>\n <p>This interface is used to represent a collection of ranges to be styled on a document.</p>\n </dd>\n <dt id=\"highlightregistry\"><a href=\"/en-US/docs/Web/API/HighlightRegistry\"><code>HighlightRegistry</code></a></dt>\n <dd>\n <p>Accessible via <a href=\"/en-US/docs/Web/API/CSS/highlights_static\" title=\"CSS.highlights\"><code>CSS.highlights</code></a>, this <a href=\"/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map\"><code>Map</code></a>-like object is used to register highlights with custom identifiers.</p>\n </dd>\n</dl>"}},{"type":"prose","value":{"id":"examples","title":"Examples","isH3":false,"content":""}},{"type":"prose","value":{"id":"highlighting_search_results","title":"Highlighting search results","isH3":true,"content":"<p>This example shows how to use the CSS Custom Highlight API to highlight search results.</p>\n<h4 id=\"html\">HTML</h4>\n<p>The HTML code snippet below defines a search field and an article with a few paragraphs of text:</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">html</span></div><pre class=\"brush: html notranslate\"><code><label>Search within text <input id=\"query\" type=\"text\" /></label>\n<article>\n <p>\n Maxime debitis hic, delectus perspiciatis laborum molestiae labore,\n deleniti, quam consequatur iure veniam alias voluptas nisi quo. Dolorem\n eaque alias, quo vel quas repudiandae architecto deserunt quidem, sapiente\n laudantium nulla.\n </p>\n <p>\n Maiores odit molestias, necessitatibus doloremque dolor illum reprehenderit\n provident nostrum laboriosam iste, tempore perferendis! Ab porro neque esse\n voluptas libero necessitatibus fugiat, ex, minus atque deserunt veniam\n molestiae tempora? Vitae.\n </p>\n <p>\n Dolorum facilis voluptate eaque eius similique ducimus dignissimos assumenda\n quos architecto. Doloremque deleniti non exercitationem rerum quam alias\n harum, nisi obcaecati corporis temporibus vero sapiente voluptatum est\n quibusdam id ipsa.\n </p>\n</article>\n</code></pre></div>\n<h4 id=\"javascript\">JavaScript</h4>\n<p>JavaScript is used to listen to the <code>input</code> event on the search field. When the event is fired, the code locates matches for the input text in the article text. It then creates ranges for the matches, and uses the CSS Custom Highlight API to create and register a <code>search-results</code> highlight object:</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">js</span></div><pre class=\"brush: js notranslate\"><code>const query = document.getElementById(\"query\");\nconst article = document.querySelector(\"article\");\n\n// Find all text nodes in the article. We'll search within\n// these text nodes.\nconst treeWalker = document.createTreeWalker(article, NodeFilter.SHOW_TEXT);\nconst allTextNodes = [];\nlet currentNode = treeWalker.nextNode();\nwhile (currentNode) {\n allTextNodes.push(currentNode);\n currentNode = treeWalker.nextNode();\n}\n\n// Listen to the input event to run the search.\nquery.addEventListener(\"input\", () => {\n // If the CSS Custom Highlight API is not supported,\n // display a message and bail-out.\n if (!CSS.highlights) {\n article.textContent = \"CSS Custom Highlight API not supported.\";\n return;\n }\n\n // Clear the HighlightRegistry to remove the\n // previous search results.\n CSS.highlights.clear();\n\n // Clean-up the search query and bail-out if\n // if it's empty.\n const str = query.value.trim().toLowerCase();\n if (!str) {\n return;\n }\n\n // Iterate over all text nodes and find matches.\n const ranges = allTextNodes\n .map((el) => {\n return { el, text: el.textContent.toLowerCase() };\n })\n .map(({ text, el }) => {\n const indices = [];\n let startPos = 0;\n while (startPos < text.length) {\n const index = text.indexOf(str, startPos);\n if (index === -1) break;\n indices.push(index);\n startPos = index + str.length;\n }\n\n // Create a range object for each instance of\n // str we found in the text node.\n return indices.map((index) => {\n const range = new Range();\n range.setStart(el, index);\n range.setEnd(el, index + str.length);\n return range;\n });\n });\n\n // Create a Highlight object for the ranges.\n const searchResultsHighlight = new Highlight(...ranges.flat());\n\n // Register the Highlight object in the registry.\n CSS.highlights.set(\"search-results\", searchResultsHighlight);\n});\n</code></pre></div>\n<h4 id=\"css\">CSS</h4>\n<p>Finally, the <code>::highlight()</code> pseudo-element is used in CSS to style the highlights:</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">css</span></div><pre class=\"brush: css notranslate\"><code>::highlight(search-results) {\n background-color: #f06;\n color: white;\n}\n</code></pre></div>\n<h4 id=\"result\">Result</h4>\n<p>The result is shown below. Type text within the search field to highlight matches in the article:</p><div class=\"code-example\"><div class=\"example-header\"></div><iframe class=\"sample-code-frame\" title=\"Highlighting search results sample\" id=\"frame_highlighting_search_results\" width=\"700\" height=\"300\" src=\"about:blank\" data-live-path=\"/en-US/docs/Web/API/CSS_Custom_Highlight_API\" data-live-id=\"highlighting_search_results\" sandbox=\"allow-same-origin allow-scripts\" loading=\"lazy\"></iframe></div>"}},{"type":"specifications","value":{"title":"Specifications","id":"specifications","isH3":false,"specifications":[{"bcdSpecificationURL":"https://drafts.csswg.org/css-highlight-api-1/","title":"CSS Custom Highlight API Module Level 1"}],"query":"api.Highlight,api.HighlightRegistry,css.selectors.highlight"}},{"type":"prose","value":{"id":"browser_compatibility","title":"Browser compatibility","isH3":false,"content":""}},{"type":"browser_compatibility","value":{"title":"api.Highlight","id":"api.Highlight","isH3":true,"query":"api.Highlight"}},{"type":"browser_compatibility","value":{"title":"api.HighlightRegistry","id":"api.HighlightRegistry","isH3":true,"query":"api.HighlightRegistry"}},{"type":"browser_compatibility","value":{"title":"css.selectors.highlight","id":"css.selectors.highlight","isH3":true,"query":"css.selectors.highlight"}},{"type":"prose","value":{"id":"see_also","title":"See also","isH3":false,"content":"<ul>\n <li><a href=\"https://css-tricks.com/css-custom-highlight-api-early-look/\" class=\"external\" target=\"_blank\">CSS Custom Highlight API: The Future of Highlighting Text Ranges on the Web</a></li>\n <li>HTML <a href=\"/en-US/docs/Web/HTML/Global_attributes/contenteditable\"><code>contentEditable</code></a> attribute</li>\n <li>CSS <a href=\"/en-US/docs/Web/CSS/Pseudo-elements\"><code>pseudo-elements</code></a></li>\n</ul>"}}],"toc":[{"text":"Concepts and usage","id":"concepts_and_usage"},{"text":"Interfaces","id":"interfaces"},{"text":"Examples","id":"examples"},{"text":"Specifications","id":"specifications"},{"text":"Browser compatibility","id":"browser_compatibility"},{"text":"See also","id":"see_also"}],"summary":"The CSS Custom Highlight API provides a mechanism for styling arbitrary text ranges on a document by using JavaScript to create the ranges, and CSS to style them.","popularity":0.0059,"modified":"2024-02-22T04:56:10.000Z","other_translations":[{"locale":"de","title":"CSS Custom Highlight API","native":"Deutsch"},{"locale":"zh-CN","title":"CSS 自定义高亮 API","native":"中文 (简体)"}],"pageType":"web-api-overview","source":{"folder":"en-us/web/api/css_custom_highlight_api","github_url":"https://github.com/mdn/content/blob/main/files/en-us/web/api/css_custom_highlight_api/index.md","last_commit_url":"https://github.com/mdn/content/commit/408aa6446554821aa52f4208e9431fa6b85083cf","filename":"index.md"},"short_title":"CSS Custom Highlight API","parents":[{"uri":"/en-US/docs/Web","title":"References"},{"uri":"/en-US/docs/Web/API","title":"Web APIs"},{"uri":"/en-US/docs/Web/API/CSS_Custom_Highlight_API","title":"CSS Custom Highlight API"}],"pageTitle":"CSS Custom Highlight API - Web APIs | MDN","noIndexing":false}}</script> <script>function gtElInit() {var lib = new google.translate.TranslateService();lib.translatePage('pl', 'ja', function () {});}</script> <script src="https://translate.google.com/translate_a/element.js?cb=gtElInit&hl=en-GB&client=wt" type="text/javascript"></script> </body> </html>

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