React学习笔记--程序调试

React学习笔记

二程序调试

前面我们搭建好了React的基本开发环境，可以编写基本的React js程序了。但完成的开发环境肯定包含调试器，怎么调试用React编写的JS程序呢？有浏览器，比如Firefox，Chrome，按F12，找到javaScript脚本，打断点，然后调试。这是调试JavaScript的基本环境，但是React由于使用了ES6的语法，在浏览器中经过Babel解析，或者在发布前就将React的代码编译成了ES5规范的JavaScript代码，我们调试时怎么能调试到自己的写的React代码呢？
前面我曾经提到使用Webpack打包发布React程序，那么我们能否借助Webpack来运行调试React程序呢？答案时肯定的。

首先我们在项目目录下安装相关的Babel，Webpack模块

npm init
npm install --save-dev webpack webpack-dev-server
npm install --save-dev react react-dom
npm install --save-dev babel-core babel-preset-react babel-preset-es2015 babel-loader babel-cli babel-plugin-transform-runtime

2.修改package.json

{
   "name": "demo1",
   "version": "1.0.0",
   "main": "webpack.config.js",
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
   "devDependencies": {
     "babel-cli": "^6.26.0",
     "babel-core": "^6.26.0",
     "babel-loader": "^6.4.1",
     "babel-plugin-transform-runtime": "^6.23.0",
     "babel-preset-es2015": "^6.24.1",
     "babel-preset-react": "^6.24.1",
     "react": "^15.6.2",
     "react-dom": "^15.6.2",
     "webpack": "^2.2.1",
     "webpack-dev-server": "^2.9.7"
   },
   "dependencies": {
     "react": "^15.6.2",
     "react-dom": "^15.6.2",
     "react-router-dom": "^4.2.2",
     "webpack-dev-server": "^2.4.1"
   },
   "presets": [
     "react"
   ],
   "author": "",
   "license": "ISC",
   "description": ""
}

3.项目下填加webpack.config.js

module.exports = {
 devtool: 'source-map',//这个配置很重要，告诉Webpack生成map.js，只有加入此配置才能在浏览器中真正调试React Js
 entry: './src/test.jsx',
 output: {
     filename: './lib/bundle.js'
 },
 module: {
     loaders: [
         {
             test: /\.js[x]?$/,
             exclude: /node_modules/,
             loader: 'babel-loader',
             query: {
                 presets: ['es2015', 'react']
             }
         }
     ]
 }
}

4..babelrc填加如下配置

{
 "presets": ["es2015","react"],
 "plugins": ["transform-runtime"],
 "comments": true
}

5.项目子目录src中创建test.jsx

import React from "react"
import ReactDOM from "react-dom"
var HelloMessage = React.createClass({
 render: function () {
     return <h1>Hello World！</h1>;
 }
});
ReactDOM.render(
 <HelloMessage />,
 document.getElementById('test')
);

6.创建index.htm，其中script直接引用webpack输出的js

<!DOCTYPE html>
<html>
 <body>
   <div id="test"></div>
   <script  src="../lib/bundle.js"></script>
 </body>
</html>

7.在console中的项目目录下运行webpack,可以看到在lib子目录下生成了bundle.js和bundle.map.js

PS D:\DEV\react\demo1> webpack
(node:9404) DeprecationWarning: loaderUtils.parseQuery() received a non-string value which can be problematic, see https://github.com/webpack/loader-utils/issues/56
parseQuery() will be replaced with getOptions() in the next major version of loader-utils.
Hash: 47d9ffef6066b3ac6378
Version: webpack 2.7.0
Time: 2131ms
           Asset    Size  Chunks                    Chunk Names
 ./lib/bundle.js  779 kB       0  [emitted]  [big]  main
./lib/bundle.js.map  942 kB       0  [emitted]         main
[28] ./~/react/lib/React.js 4.96 kB {0} [built]
[77] ./~/babel-runtime/helpers/typeof.js 1.07 kB {0} [built]
[122] ./~/babel-runtime/core-js/object/get-prototype-of.js 104 bytes {0} [built]
[123] ./~/babel-runtime/helpers/classCallCheck.js 208 bytes {0} [built]
[124] ./~/babel-runtime/helpers/createClass.js 904 bytes {0} [built]
[125] ./~/babel-runtime/helpers/inherits.js 1.11 kB {0} [built]
[126] ./~/babel-runtime/helpers/possibleConstructorReturn.js 542 bytes {0} [built]
[127] ./~/react-dom/index.js 59 bytes {0} [built]
[128] ./~/react/react.js 56 bytes {0} [built]
[129] ./src/test.jsx 5.21 kB {0} [built]
[130] ./~/babel-runtime/core-js/object/create.js 94 bytes {0} [built]
[131] ./~/babel-runtime/core-js/object/define-property.js 103 bytes {0} [built]
[132] ./~/babel-runtime/core-js/object/set-prototype-of.js 104 bytes {0} [built]
[137] ./~/babel-runtime/~/core-js/library/fn/object/get-prototype-of.js 125 bytes {0} [built]
[199] ./~/react-dom/lib/ReactDOM.js 5.05 kB {0} [built]
 + 254 hidden modules

8.启动webpack-dev-server,访问http://localhost:8080就可以看到helloword了。

PS D:\DEV\react\demo1> webpack-dev-server --inline
Project is running at http://localhost:8080/
webpack output is served from /
(node:4340) DeprecationWarning: loaderUtils.parseQuery() received a non-string value which can be problematic, see https://github.com/webpack/loader-utils/issues/56
parseQuery() will be replaced with getOptions() in the next major version of loader-utils.
Hash: 64a0de3cefb7972eab47
Version: webpack 2.7.0
Time: 2449ms
           Asset     Size  Chunks                    Chunk Names
 ./lib/bundle.js   1.1 MB       0  [emitted]  [big]  main
./lib/bundle.js.map  1.32 MB       0  [emitted]         main
chunk    {0} ./lib/bundle.js, ./lib/bundle.js.map (main) 1.07 MB [entry] [rendered]
[124] ./src/test.jsx 5.21 kB {0} [built]
[125] (webpack)-dev-server/client?http://localhost:8080 7.95 kB {0} [built]
[130] ./~/babel-runtime/core-js/object/get-prototype-of.js 104 bytes {0} [built]
[134] ./~/babel-runtime/helpers/classCallCheck.js 208 bytes {0} [built]
[135] ./~/babel-runtime/helpers/createClass.js 904 bytes {0} [built]
[136] ./~/babel-runtime/helpers/inherits.js 1.11 kB {0} [built]
[137] ./~/babel-runtime/helpers/possibleConstructorReturn.js 542 bytes {0} [built]
[198] ./~/react-dom/index.js 59 bytes {0} [built]
[282] ./~/react/react.js 56 bytes {0} [built]
[284] ./~/strip-ansi/index.js 161 bytes {0} [built]
[285] ./~/url/url.js 23.3 kB {0} [built]
[287] (webpack)-dev-server/client/overlay.js 3.73 kB {0} [built]
[290] (webpack)/hot nonrecursive ^\.\/log$ 160 bytes {0} [built]
[291] (webpack)/hot/emitter.js 77 bytes {0} [built]
[292] multi (webpack)-dev

9.打开firefox（本人使用firefox浏览器进行调试），在调试器左侧资源栏中可以找到webpack相关的资源，找到自己编写的test.jsx，打上断点，就可以像调试ES5一样调试自己写的React代码了。
[ react-debug-png

本文链接：http://www.cnblogs.com/tom-lau/p/8032323.html

React学习笔记--程序调试