kef-builder-buffet/webpack/plugins/wraper-webpack-plugin.js

buffet-builder构建工具

'use strict';
// const ConcatSource = require('webpack/lib/ConcatSource');

module.exports = class WrapperPlugin {
  /**
   * WraperPlugin
   * @param  {Object} options 选项
   * @param {string|function} options.header 前内容
   * @param {string|function} options.footer 后内容
   * @constructor
   */
  constructor(options) {

    this.header = options.hasOwnProperty('header') ? options.header : '';
    this.footer = options.hasOwnProperty('footer') ? options.footer : '';
  }

  apply(compiler) {
    const header = this.header;
    const footer = this.footer;
    const entry = compiler.options.entry;

    const wrapFile = (compilation, fileName) => {
      // chunks 在 apply SingleEntryPlugin 后会向 chunks push 
      // 对应的当前模块, 根据模块的 name 也就是 entryName 
      const headerContent = (typeof header === 'function') ?
        header(fileName, entry, compilation.chunks) : header;
      const footerContent = (typeof footer === 'function') ?
        footer(fileName, entry, compilation.chunks) : footer;
      const initSource = compilation.assets[fileName].source();
      const resSource = `${String(headerContent)}${initSource}${String(footerContent)}`;
      // compilation.assets[fileName] = new ConcatSource(
      //   String(headerContent),
      //   compilation.assets[fileName],
      //   String(footerContent));

      compilation.assets[fileName] = {
        source() { // 写入文件时必写项
          return resSource;
        },
        size() { // 写入文件时必写项
          return resSource.length
        }
      }
    };

    const wrapChunks = (compilation, chunks) => {
      chunks.forEach((chunk) => {
        chunk.files.forEach((fileName) => {
          wrapFile(compilation, fileName);
        });
      });
    };

    compiler.plugin('compilation', (compilation) => {
      // 优化 chunk 的生成资源
      compilation.plugin('optimize-chunk-assets', (chunks, done) => {
        wrapChunks(compilation, chunks, footer, header);
        done();
      });
    });
  }
};