script-ext-html-webpack-plugin

Script Extension for HTML Webpack Plugin

Enhances html-webpack-plugin functionality with async,defer and type="module" attributes for <script> elements.

This is an extension plugin for the webpack plugin html-webpack-plugin - a plugin that simplifies the creation of HTML files to serve your webpack bundles.

The raw html-webpack-plugin creates all <script> elements as synchronous. This plugin allows you to define which scripts should have the async and defer attributes.

Installation

Install the plugin with npm:

$ npm install --save-dev script-ext-html-webpack-plugin

Basic Usage

Add the plugin to your webpack config as follows:

plugins: [
  new HtmlWebpackPlugin(),
  new ScriptExtHtmlWebpackPlugin()
]  

The above configuration will actually do nothing due to the configuration defaults. Some more useful scenarios:

All scripts set to async:

plugins: [
  new HtmlWebpackPlugin(),
  new ScriptExtHtmlWebpackPlugin({
    defaultAttribute: 'async'
  })
]  

All scripts set to async except 'first.js' which is sync:

plugins: [
  new HtmlWebpackPlugin(),
  new ScriptExtHtmlWebpackPlugin({
    sync: ['first.js'],
    defaultAttribute: 'async'
  })
]  

Configuration offers much more complex options:

Configuration

You must pass a hash of configuration options to the plugin to cause the addition of attributes:

• sync: array of String's and/or RegExp's defining script names that should have no attribute (default: []);
• async: array of String's and/or RegExp's defining script names that should have an async attribute (default: []);
• defer: array of String's and/or RegExp's defining script names that should have a defer attribute (default: []);
• defaultAttribute: 'sync' | 'async' | 'defer' The default attribute to set - 'sync' actually results in no attribute (default: 'sync');
• module: array of String's and/or RegExp's defining script names that should have a type="module" attribute (default: []).

In the arrays a String value matches if it is a substring of the script name.

In more complicated use cases it may prove difficult to ensure that the pattern matching for different attributes are mutually exclusive. To prevent confusion, the plugin operates a simple precedence model:

1. if a script name matches a RegEx or String from the sync option, it will have no attribute;

2. if a script name matches a Regex or String from the async option, it will have the async attribute, unless it matched condition 1;

3. if a script name matches a Regex or String from the defer option, it will have the defer attribute, unless it matched conditions 1 or 2;

4. if a script name does not match any of the previous conditions, it will have the `defaultAttribute' attribute.

The module attribute is independent of these rules.

Some Examples:

All scripts with 'important' in their name are sync and all others set to defer:

plugins: [
  new HtmlWebpackPlugin(),
  new ScriptExtHtmlWebpackPlugin({
    sync: ['important'],
    defaultAttribute: 'defer'
  })
]  

Alternatively, using a regular expression:

plugins: [
  new HtmlWebpackPlugin(),
  new ScriptExtHtmlWebpackPlugin({
    sync: [/important/],
    defaultAttribute: 'defer'
  })
]  

All scripts with 'mod' in their name are async and type 'module', all others are sync (no explicit setting for this as it is the default):

plugins: [
  new HtmlWebpackPlugin(),
  new ScriptExtHtmlWebpackPlugin({
    async: ['mod'],
    module: ['mod']
  })
]  

And so on, to craziness:

plugins: [
  new HtmlWebpackPlugin(),
  new ScriptExtHtmlWebpackPlugin({
    sync: [/imp(1|2){1,3}}/, 'initial'],
    defer: ['slow', /big.*andslow/],
    module: [/^((?!sync).)*/, 'mod']
    defaultAttribute: 'async'
  })
]  

Any problems with real-world examples, just raise an issue.