add some comments

Author: xiaoiver

README.md

@@ -6,22 +6,29 @@ vue-skeleton-webpack-plugin
 
 [![NPM](https://nodei.co/npm/vue-skeleton-webpack-plugin.png?downloads=true&downloadRank=true&stars=true)](https://nodei.co/npm/vue-skeleton-webpack-plugin/)
 
-基于 vue 的 webpack 插件，为单页/多页应用生成 skeleton，提升首屏展示体验。
+这是一个基于 Vue 的 webpack 插件，为单页/多页应用生成骨架屏 skeleton，减少白屏时间，在页面完全渲染之前提升用户感知体验。
 
 ## 基本实现
 
-参考了[Ele.me的这篇文章](https://medium.com/elemefe/upgrading-ele-me-to-progressive-web-app-2a446832e509)，
+参考了[饿了么的 PWA 升级实践](https://huangxuan.me/2017/07/12/upgrading-eleme-to-pwa/)一文，
 使用服务端渲染在构建时渲染 skeleton 组件，将 DOM 和样式内联到最终输出的 html 中。
 
 另外，为了开发时调试方便，会将对应路由写入`router.js`中，可通过`/skeleton`路由访问。
 
+插件具体实现可参考[我的这篇文章](https://xiaoiver.github.io/coding/2017/07/30/%E4%B8%BAvue%E9%A1%B9%E7%9B%AE%E6%B7%BB%E5%8A%A0%E9%AA%A8%E6%9E%B6%E5%B1%8F.html)
+
 ## 使用方法
 
 安装：
 ```bash
 npm install vue-skeleton-webpack-plugin
 ```
 
+运行测试用例：
+```bash
+npm run test
+```
+
 在 webpack 中引入插件：
 ```js
 // webpack.conf.js

src/index.js

@@ -13,12 +13,6 @@ const DEFAULT_PLUGIN_OPTIONS = {
     insertAfter: '<div id="app">'
 };
 
-const DEFAULT_LOADER_OPTIONS = {
-    importTemplate: 'import [nameCap] from \'@/pages/[nameCap].vue\';',
-    routePathTemplate: '/skeleton-[name]',
-    insertAfter: 'routes: ['
-};
-
 class SkeletonPlugin {
 
     constructor(options = {}) {
@@ -43,10 +37,12 @@ class SkeletonPlugin {
 
         compiler.plugin('compilation', compilation => {
 
+            // add listener for html-webpack-plugin
             compilation.plugin('html-webpack-plugin-before-html-processing', (htmlPluginData, callback) => {
 
                 let usedChunks = htmlPluginData.plugin.options.chunks;
                 let entryKey;
+
                 // find current processing entry
                 if (Array.isArray(usedChunks)) {
                     entryKey = Object.keys(skeletonEntries);
@@ -56,6 +52,7 @@ class SkeletonPlugin {
                     entryKey = 'app';
                 }
 
+                // set current entry & output in webpack config
                 webpackConfig.entry = skeletonEntries[entryKey];
                 webpackConfig.output.filename = `skeleton-${entryKey}.js`;
 
@@ -76,8 +73,7 @@ class SkeletonPlugin {
     static loader(ruleOptions = {}) {
         return Object.assign(ruleOptions, {
             loader: require.resolve('./loader'),
-            options: Object.assign({}, DEFAULT_LOADER_OPTIONS,
-                Object.assign({}, ruleOptions.options))
+            options: Object.assign({}, ruleOptions.options)
         });
     }
 }

src/loader.js

@@ -1,5 +1,7 @@
 /**
  * @file loader
+ * @desc Insert route of skeleton into router.js, so that developer can
+ * visit route path in dev mode to debug skeleton components
  * @author panyuqi <panyuqi@baidu.com>
  */
 
@@ -8,34 +10,47 @@
 const loaderUtils = require('loader-utils');
 const insertAt = require('./util').insertAt;
 
+const DEFAULT_LOADER_OPTIONS = {
+    // template of importing skeleton component
+    importTemplate: 'import [nameCap] from \'@/pages/[nameCap].vue\';',
+    // template of route path
+    routePathTemplate: '/skeleton-[name]',
+    // position to insert route object in router.js file
+    insertAfter: 'routes: ['
+};
+
 const ENTRY_NAME_HOLDER = /\[name\]/gi;
 const ENTRY_NAME_CAP_HOLDER = /\[nameCap\]/gi;
 
 module.exports = function (source) {
-    const options = loaderUtils.getOptions(this);
+    const options = Object.assign({}, DEFAULT_LOADER_OPTIONS, loaderUtils.getOptions(this));
     let {entry, importTemplate, routePathTemplate, insertAfter} = options;
 
-    // position to insert in router.js
+    // find position to insert in router.js
     let routesPos = source.indexOf(insertAfter) + insertAfter.length;
 
-    if (!Array.isArray(entry)) {
-        entry = [entry];
-    }
+    entry = Array.isArray(entry) ? entry : [entry];
 
     entry.forEach(entryName => {
-        // capitalize first letter
+        // capitalize first letter in entryName eg.skeleton -> Skeleton
         let entryCap = entryName.replace(/([a-z])(.*)/, (w, firstLetter, rest) => firstLetter.toUpperCase() + rest);
-        // route path
-        let skeletonRoutePath = routePathTemplate.replace(ENTRY_NAME_HOLDER, entryName)
-            .replace(ENTRY_NAME_CAP_HOLDER, entryCap);
-        let importExpression = importTemplate.replace(ENTRY_NAME_HOLDER, entryName)
-            .replace(ENTRY_NAME_CAP_HOLDER, entryCap);
+
+        // replace placeholder in routeTpl and importTpl
+        let [skeletonRoutePath, importExpression] = [routePathTemplate, importTemplate]
+            .map(pathStr => pathStr.replace(ENTRY_NAME_HOLDER, entryName)
+                .replace(ENTRY_NAME_CAP_HOLDER, entryCap));
+
+        // route object to insert
         let routeExpression = `{
             path: '${skeletonRoutePath}',
             name: '${entryName}-skeleton',
             component: ${entryCap}
         },`;
+
+        // insert route object into routes array
         source = insertAt(source, routeExpression, routesPos);
+
+        // insert import sentence in the head
         source += importExpression;
     });
 

src/ssr.js

@@ -1,5 +1,6 @@
 /**
  * @file ssr
+ * @desc Use vue ssr to render skeleton components. The result contains html and css.
  * @author panyuqi <panyuqi@baidu.com>
  */
 
@@ -20,7 +21,7 @@ module.exports = serverWebpackConfig => new Promise((resolve, reject) => {
 
     console.log(`Generate skeleton for ${outputBasename}...`);
 
-    // extract css
+    // extract css into a single file
     serverWebpackConfig.plugins.push(new ExtractTextPlugin({
         filename: outputCssBasename
     }));
@@ -47,8 +48,9 @@ module.exports = serverWebpackConfig => new Promise((resolve, reject) => {
 
         let bundle = mfs.readFileSync(outputPath, 'utf-8');
         let skeletonCss = mfs.readFileSync(outputCssPath, 'utf-8');
+        // create renderer with bundle
         let renderer = createBundleRenderer(bundle);
-        // ssr skeleton
+        // use vue ssr to render skeleton
         renderer.renderToString({}, (err, skeletonHtml) => {
             if (err) {
                 reject(err);