160 lines
8.4 KiB
Markdown
160 lines
8.4 KiB
Markdown
# minify-html-literals
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_Minify HTML markup inside JavaScript template literal strings._
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[](https://www.npmjs.com/package/minify-html-literals)
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[](https://travis-ci.com/asyncLiz/minify-html-literals)
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[](https://coveralls.io/github/asyncLiz/minify-html-literals?branch=master)
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## Why?
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Template literals are often used in JavaScript to write HTML and CSS markup (ex. [lit-html](https://www.npmjs.com/package/lit-html)). This library allows a developer to minify markup that is normally ignored by JavaScript minifiers.
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## Usage
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```js
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import { minifyHTMLLiterals } from 'minify-html-literals';
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// const minifyHTMLLiterals = require('minify-html-literals').minifyHTMLLiterals
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const result = minifyHTMLLiterals(
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`function render(title, items) {
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return html\`
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<style>
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.heading {
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color: blue;
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}
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</style>
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<h1 class="heading">\${title}</h1>
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<ul>
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\${items.map(item => {
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return getHTML()\`
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<li>\${item}</li>
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\`;
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})}
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</ul>
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\`;
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}`,
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{
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fileName: 'render.js'
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}
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);
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console.log(result.code);
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// function render(title, items) {
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// return html`<style>.heading{color:#00f}</style><h1 class=heading>${title}</h1><ul>${items.map(item => {
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// return getHTML()`<li>${item}</li>`;
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// })}</ul>`;
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// }
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console.log(result.map);
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// {
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// "version": 3,
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// "file": "render.js.map",
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// "sources": ["render.js"],
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// "sourcesContent": [null],
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// "names": [],
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// "mappings": "AAAA;gBACgB,qDAMU,QAAQ,SAE1B;2BACmB,IACX,OAAO,KACb;WACC,KAEP;"
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// }
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```
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### ES5 Transpiling Warning
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Be sure to minify template literals _before_ transpiling to ES5. Otherwise, the API will not be able to find any template literal (`` `${}` ``) strings.
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## Supported Source Syntax
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- JavaScript
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- TypeScript
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## Options
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### Basic
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The following options are common to typical use cases.
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| Property | Type | Default | Description |
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| --------------------------- | -------------------------------------------------------------------------------------------- | ------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
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| `fileName` | string | | _Required._ The name of the file, used for syntax parsing and source maps. |
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| `minifyOptions?` | [html-minifier options](https://www.npmjs.com/package/html-minifier#options-quick-reference) | `defaultMinifyOptions` | Defaults to production-ready minification. |
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| `minifyOptions?.minifyCSS?` | [clean-css options](https://www.npmjs.com/package/clean-css#constructor-options) | `defaultMinifyCSSOptions` | Uses clean-css defaults. |
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| `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). |
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| `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). |
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### Advanced
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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.
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| Property | Type | Default | Description |
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| ----------------------- | ------------------------------------------------------------------------- | -------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------- |
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| `generateSourceMap?` | boolean or `(ms: MagicString, fileName: string) => SourceMap | undefined` | `defaultGenerateSourceMap` | Set to `false` to disable source maps, or a custom function to control how source maps are generated from a `MagicString` instance. |
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| `strategy?` | object | `defaultStrategy` | An object with methods defining how to minify HTML. The default strategy uses [html-minifier](https://www.npmjs.com/package/html-minifier). |
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| `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. |
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| `parseLiterals?` | function | [parse-literals](https://www.npmjs.com/package/parse-literals) | Override the function used to parse template literals from a source string. |
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| `parseLiteralsOptions?` | object | | Additional options to pass to `parseLiterals()` |
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| `MagicString?` | function | [MagicString](https://www.npmjs.com/package/magic-string) | Override the MagicString-like constructor to use for manipulating the source string and generating source maps. |
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## Customization Examples
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### Minify non-tagged templates
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> This is particularly useful for libraries that define templates without using tags, such as Polymer's `<dom-module>`.
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```js
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import { minifyHTMLLiterals, defaultShouldMinify } from 'minify-html-literals';
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minifyHTMLLiterals(
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`
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template.innerHTML = \`
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<dom-module id="custom-styles">
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<style>
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html {
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--custom-color: blue;
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}
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</style>
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</dom-module>
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\`;
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`,
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{
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fileName: 'render.js',
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shouldMinify(template) {
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return (
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defaultShouldMinify(template) ||
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template.parts.some(part => {
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return part.text.includes('<dom-module>');
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})
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);
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}
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}
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);
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```
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### Do not minify CSS
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```js
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import { minifyHTMLLiterals, defaultMinifyOptions } from 'minify-html-literals';
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minifyHTMLLiterals(source, {
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fileName: 'render.js',
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minifyOptions: {
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...defaultMinifyOptions,
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minifyCSS: false
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},
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shouldMinifyCSS: () => false
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});
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```
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### Modify generated SourceMap
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```js
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minifyHTMLLiterals(source, {
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fileName: 'render.js',
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generateSourceMap(ms, fileName) {
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return ms.generateMap({
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file: `${fileName}-converted.map`, // change file name
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source: fileName,
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includeContent: true // include source contents
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});
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}
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});
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```
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