A webpack plugin that wraps output files (chunks) with custom text or code.

Installation

Install locally using npm:
npm i -D wrapper-webpack-plugin

Webpack compatibility

Version 2 of this plugin only works with webpack >=4.
For webpack <4 use version 1 of the plugin with npm i -D wrapper-webpack-plugin@1

Usage

The WrapperPlugin class has a single parameter, an object with a header and/or footer properties. Header text will be prepended to the output file, footer text will be appended. These can be either a string or a function. A string will simply be a appended/prepended to the file output. A function is expected to return a string, and will receive the name of the output file as an argument.

An optional test property (a string or a RegExp object) can control which output files are affected; otherwise all output files will be wrapped.

New in 2.1:
The optional afterOptimizations property can be used to avoid having the added text affected by the optimization stage, e.g. if you don't want it to be minified.

API

function WrapperPlugin({
    test: string | RegExp,
    header: string | function,
    footer: string | function,
    afterOptimizations: bool // default: false
})

Example configuration #1

Wraps bundle files with '.js' extension in a self invoking function and enables strict mode:

const WrapperPlugin = require('wrapper-webpack-plugin');

module.exports = {
  // other webpack config here
  
  plugins: [
    // strict mode for the whole bundle
    new WrapperPlugin({
      test: /\.js$/, // only wrap output of bundle files with '.js' extension 
      header: '(function () { "use strict";\n',
      footer: '\n})();'
    })
  ]
};

Example configuration #2

Prepends bundles with a doc comment:

const WrapperPlugin = require('wrapper-webpack-plugin');

module.exports = {
  // other webpack config here
  
  plugins: [
    new WrapperPlugin({
      header: function (fileName) {
        return '/*! file: ' + fileName + ', created by dev123 */\n';
      }
    })
  ]
};

Example configuration #3

Accessing file name, build hash, and chunk hash at runtime.

const WrapperPlugin = require('wrapper-webpack-plugin');

module.exports = {
  // other webpack config here
	
  output: {
    filename: '[name].[chunkhash].js'
  },
  plugins: [
    new WrapperPlugin({
      header: `(function (FILE_NAME, BUILD_HASH, CHUNK_HASH) {`,
      footer(fileName, args) {
        return `})('${fileName}', '${args.hash}', '${args.chunkhash}');`;
        // note: args.hash and args.chunkhash correspond to the [hash] and [chunkhash] 
        // placeholders you can specify in the output.filename option.
      }
    })
  ]
};

Example configuration #4

Keeping header in a separate file:

file: header.js

/*!
 * my awesome app!
 */

file: webpack.config

const fs = require('fs');
 WrapperPlugin = require('wrapper-webpack-plugin');

const headerDoc = fs.readFileSync('./header.js', 'utf8');

module.exports = {
  // other webpack config here

  plugins: [
    new WrapperPlugin({
      header: headerDoc
    })
  ]
};

Example configuration #5

A slightly more complex example using lodash templates:

const WrapperPlugin = require('wrapper-webpack-plugin');
const template = require('lodash.template');
const pkg = require('./package.json');

const tpl = '/*! <%= name %> v<%= version %> | <%= author %> */\n';

module.exports = {
  // other webpack config here

  plugins: [
    new WrapperPlugin({
      header: template(tpl)(pkg)
    })
  ]
};

Compatibility with other plugins

This plugin should play nicely with most other plugins. E.g. adding the webpack.optimize.UglifyJsPlugin plugin to the plugins array after the WrapperPlugin will result in the wrapper text also being minified.

License

ISC