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    1.3.5 • Public • Published


    Minify HTML markup inside JavaScript template literal strings.

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    Template literals are often used in JavaScript to write HTML and CSS markup (ex. lit-html). This library allows a developer to minify markup that is normally ignored by JavaScript minifiers.


    import { minifyHTMLLiterals } from 'minify-html-literals';
    // const minifyHTMLLiterals = require('minify-html-literals').minifyHTMLLiterals
    const result = minifyHTMLLiterals(
      `function render(title, items) {
        return html\`
            .heading {
              color: blue;
          <h1 class="heading">\${title}</h1>
            \${ => {
              return getHTML()\`
        fileName: 'render.js'
    //  function render(title, items) {
    //    return html`<style>.heading{color:#00f}</style><h1 class=heading>${title}</h1><ul>${ => {
    //          return getHTML()`<li>${item}</li>`;
    //        })}</ul>`;
    //  }
    // {
    //   "version": 3,
    //   "file": "",
    //   "sources": ["render.js"],
    //   "sourcesContent": [null],
    //   "names": [],
    // }

    ES5 Transpiling Warning

    Be sure to minify template literals before transpiling to ES5. Otherwise, the API will not be able to find any template literal (`${}`) strings.

    Supported Source Syntax

    • JavaScript
    • TypeScript



    The following options are common to typical use cases.

    Property Type Default Description
    fileName string Required. The name of the file, used for syntax parsing and source maps.
    minifyOptions? html-minifier options defaultMinifyOptions Defaults to production-ready minification.
    minifyOptions?.minifyCSS? clean-css options defaultMinifyCSSOptions Uses clean-css defaults.
    shouldMinify? function defaultShouldMinify A function that determines whether or not an HTML template should be minified. Defaults to minify all tagged templates whose tag name contains "html" (case insensitive).
    shouldMinifyCSS? function defaultShouldMinifyCSS A function that determines whether or not a CSS template should be minified. Defaults to minify all tagged templates whose tag name contains "css" (case insensitive).


    All aspects of the API are exposed and customizable. The following options will not typically be used unless you need to change how a certain aspect of the API handles a use case.

    Property Type Default Description
    generateSourceMap? boolean or `(ms: MagicString, fileName: string) => SourceMap undefined` defaultGenerateSourceMap
    strategy? object defaultStrategy An object with methods defining how to minify HTML. The default strategy uses html-minifier.
    validate? boolean or object defaultValidation Set to false to disable strategy validation checks, or to a custom set of validation functions. This is only useful when implementing a custom strategy.
    parseLiterals? function parse-literals Override the function used to parse template literals from a source string.
    parseLiteralsOptions? object Additional options to pass to parseLiterals()
    MagicString? function MagicString Override the MagicString-like constructor to use for manipulating the source string and generating source maps.

    Customization Examples

    Minify non-tagged templates

    This is particularly useful for libraries that define templates without using tags, such as Polymer's <dom-module>.

    import { minifyHTMLLiterals, defaultShouldMinify } from 'minify-html-literals';
        template.innerHTML = \`
          <dom-module id="custom-styles">
              html {
                --custom-color: blue;
        fileName: 'render.js',
        shouldMinify(template) {
          return (
            defaultShouldMinify(template) ||
   => {
              return part.text.includes('<dom-module>');

    Do not minify CSS

    import { minifyHTMLLiterals, defaultMinifyOptions } from 'minify-html-literals';
    minifyHTMLLiterals(source, {
      fileName: 'render.js',
      minifyOptions: {
        minifyCSS: false
      shouldMinifyCSS: () => false

    Modify generated SourceMap

    minifyHTMLLiterals(source, {
      fileName: 'render.js',
      generateSourceMap(ms, fileName) {
        return ms.generateMap({
          file: `${fileName}`, // change file name
          source: fileName,
          includeContent: true // include source contents


    npm i minify-html-literals

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