vue-cli 中CommonsChunkPlugin配置的解释

Question

第一个CommonsChunkPlugin的应用规定了哪些module会被打包进这个name为vendor的CommonChunk里，比如jquery moment lodash 等。对吗？

// split vendor js into its own file

    new webpack.optimize.CommonsChunkPlugin({
      name: 'vendor',
      minChunks: function (module, count) {
        // any required modules inside node_modules are extracted to vendor
        return (
          module.resource &&
          /\.js$/.test(module.resource) &&
          module.resource.indexOf(
            path.join(__dirname, '../node_modules')
          ) === 0
        )
      }
    })
    
    

第二个：

// extract webpack runtime and module manifest to its own file in order to
    // prevent vendor hash from being updated whenever app bundle is updated
    new webpack.optimize.CommonsChunkPlugin({
      name: 'manifest',
      chunks: ['vendor']
    })
    

从vendor里 提取 manifest。 manifest生成的代码如下：

/******/ (function(modules) { // webpackBootstrap
/******/     // install a JSONP callback for chunk loading
/******/     var parentJsonpFunction = window["webpackJsonp"];
/******/     window["webpackJsonp"] = function webpackJsonpCallback(chunkIds, moreModules, executeModules) {
/******/         // add "moreModules" to the modules object,
/******/         // then flag all "chunkIds" as loaded and fire callback
/******/         var moduleId, chunkId, i = 0, resolves = [], result;
/******/         for(;i < chunkIds.length; i++) {
/******/             chunkId = chunkIds[i];
/******/             if(installedChunks[chunkId]) {
/******/                 resolves.push(installedChunks[chunkId][0]);
/******/             }
/******/             installedChunks[chunkId] = 0;
/******/         }
/******/         for(moduleId in moreModules) {
/******/             if(Object.prototype.hasOwnProperty.call(moreModules, moduleId)) {
/******/                 modules[moduleId] = moreModules[moduleId];
/******/             }
/******/         }
/******/         if(parentJsonpFunction) parentJsonpFunction(chunkIds, moreModules, executeModules);
/******/         while(resolves.length) {
/******/             resolves.shift()();
/******/         }
/******/         if(executeModules) {
/******/             for(i=0; i < executeModules.length; i++) {
/******/                 result = __webpack_require__(__webpack_require__.s = executeModules[i]);
/******/             }
/******/         }
/******/         return result;
/******/     };
/******/
/******/     // The module cache
/******/     var installedModules = {};
/******/
/******/     // objects to store loaded and loading chunks
/******/     var installedChunks = {
/******/         2: 0
/******/     };
/******/
/******/     // The require function
/******/     function __webpack_require__(moduleId) {
/******/
/******/         // Check if module is in cache
/******/         if(installedModules[moduleId]) {
/******/             return installedModules[moduleId].exports;
/******/         }
/******/         // Create a new module (and put it into the cache)
/******/         var module = installedModules[moduleId] = {
/******/             i: moduleId,
/******/             l: false,
/******/             exports: {}
/******/         };
/******/
/******/         // Execute the module function
/******/         modules[moduleId].call(module.exports, module, module.exports, __webpack_require__);
/******/
/******/         // Flag the module as loaded
/******/         module.l = true;
/******/
/******/         // Return the exports of the module
/******/         return module.exports;
/******/     }
/******/
/******/     // This file contains only the entry chunk.
/******/     // The chunk loading function for additional chunks
/******/     __webpack_require__.e = function requireEnsure(chunkId) {
/******/         var installedChunkData = installedChunks[chunkId];
/******/         if(installedChunkData === 0) {
/******/             return new Promise(function(resolve) { resolve(); });
/******/         }
/******/
/******/         // a Promise means "currently loading".
/******/         if(installedChunkData) {
/******/             return installedChunkData[2];
/******/         }
/******/
/******/         // setup Promise in chunk cache
/******/         var promise = new Promise(function(resolve, reject) {
/******/             installedChunkData = installedChunks[chunkId] = [resolve, reject];
/******/         });
/******/         installedChunkData[2] = promise;
/******/
/******/         // start chunk loading
/******/         var head = document.getElementsByTagName('head')[0];
/******/         var script = document.createElement('script');
/******/         script.type = 'text/javascript';
/******/         script.charset = 'utf-8';
/******/         script.async = true;
/******/         script.timeout = 120000;
/******/
/******/         if (__webpack_require__.nc) {
/******/             script.setAttribute("nonce", __webpack_require__.nc);
/******/         }
/******/         script.src = __webpack_require__.p + "static/js/" + chunkId + "." + {"0":"9bb283c0a024a4e9b573","1":"8fa79f37b4e6118ed1e1"}[chunkId] + ".js";
/******/         var timeout = setTimeout(onScriptComplete, 120000);
/******/         script.onerror = script.onload = onScriptComplete;
/******/         function onScriptComplete() {
/******/             // avoid mem leaks in IE.
/******/             script.onerror = script.onload = null;
/******/             clearTimeout(timeout);
/******/             var chunk = installedChunks[chunkId];
/******/             if(chunk !== 0) {
/******/                 if(chunk) {
/******/                     chunk[1](new Error('Loading chunk ' + chunkId + ' failed.'));
/******/                 }
/******/                 installedChunks[chunkId] = undefined;
/******/             }
/******/         };
/******/         head.appendChild(script);
/******/
/******/         return promise;
/******/     };
/******/
/******/     // expose the modules object (__webpack_modules__)
/******/     __webpack_require__.m = modules;
/******/
/******/     // expose the module cache
/******/     __webpack_require__.c = installedModules;
/******/
/******/     // define getter function for harmony exports
/******/     __webpack_require__.d = function(exports, name, getter) {
/******/         if(!__webpack_require__.o(exports, name)) {
/******/             Object.defineProperty(exports, name, {
/******/                 configurable: false,
/******/                 enumerable: true,
/******/                 get: getter
/******/             });
/******/         }
/******/     };
/******/
/******/     // getDefaultExport function for compatibility with non-harmony modules
/******/     __webpack_require__.n = function(module) {
/******/         var getter = module && module.__esModule ?
/******/             function getDefault() { return module['default']; } :
/******/             function getModuleExports() { return module; };
/******/         __webpack_require__.d(getter, 'a', getter);
/******/         return getter;
/******/     };
/******/
/******/     // Object.prototype.hasOwnProperty.call
/******/     __webpack_require__.o = function(object, property) { return Object.prototype.hasOwnProperty.call(object, property); };
/******/
/******/     // __webpack_public_path__
/******/     __webpack_require__.p = "/";
/******/
/******/     // on error function for async loading
/******/     __webpack_require__.oe = function(err) { console.error(err); throw err; };
/******/ })
/************************************************************************/
/******/ ([]);
//# sourceMappingURL=manifest.49aaaa7977b74c31349c.js.map

manifest好像是分块加载js的。具体不太清楚，有人详细了解这个吗？

Answer 1

vender是提取公共模块，如vue,lodash之类的第三方库，而 manifest则负责各个模块之间的交互。
https://doc.webpack-china.org...
https://doc.webpack-china.org...

其实 manifest的 “载货单，货单”的中文释义也能够帮助我们理解其作用。

再附一篇文章吧 https://survivejs.com/webpack...

When webpack writes bundles, it maintains a manifest as well. You can find it in the generated vendor bundle in this project. The manifest describes what files webpack should load. It's possible to extract it and start loading the files of the project faster instead of having to wait for the vendor bundle to be loaded.

If the hashes webpack generates change, then the manifest changes as well. As a result, the contents of the vendor bundle change, and become invalidated. The problem can be eliminated by extracting the manifest to a file of its own or by writing it inline to the index.html of the project.

大概意思就是说，本来webpack在打包的时候本来就有 manifest。如果不把它提取出来的话，如果你自己写的代码发生变化，提取出来的 vender也会发生变化，这样就失去了vender的意义。理想的是，自己写的代码变化，提取出来的manifest发生变化，而vender是不会发生变化，方便浏览器充分利用缓存。