React 基本概念1-1(搭配webpack)

前一章我們使用codepen與babel的cdn來幫我們compile我們寫的ES6與React的JSX語法，但我們開發時通常會使用webpack結合babel與一些plugin來幫我們做compile

建立環境

npm install webpack -g

npm install nodemon -g (在更改程式時自動執行server，與forever類似，但forever遇到錯誤也不會停止)

1.裡面放入package.json

{
    "name": "react-learning",
    "version": "1.0.0",
    "description": "A simple app",
    "scripts": {
        "test": "echo \"Error: no test specified\" && exit 1",
        "serve": "nodemon server/server.js --ignore ./components"
    },
    "repository": {
        "type": "git",
        "url": ""
    },
    "author": "",
    "license": "ISC",
    "dependencies": {
        "babel-core": "*",
        "babel-loader": "*",
        "babel-preset-es2015": "*",
        "babel-preset-react": "*",
        "express": "*",
        "react": "*",
        "react-dom": "*",
        "webpack": "*"
    }
}

之後輸入npm install

  --client
  --components
  --server
package.json

2.接著在server目錄下新增server.js

var express = require('express');
var path = require('path');

var app = express();

app.use(express.static('./dist'));

app.use('/', function (req, res) {
  res.sendFile(path.resolve('client/index.html'));
});

var port = 3000;

app.listen(port, function(error) {
  if (error) throw error;
  console.log("Express server listening on port", port);
});

3.在client資料夾內加入index.html

<!DOCTYPE html>
    <html lang="en">
    <head>
      <meta charset="UTF-8">
    <title>React example</title>
    </head>
    <body>
      <h1>hihi !</h1>
      <div id="app"></div>
      <script src="bundle.js"></script>
    </body>
</html>

4.新增webpack 配置文件webpack.config.js

module.exports = {
  devtool: 'inline-source-map',
  entry: ['./client/client.js'],
  output: {
    path: './dist',
    filename: 'bundle.js',
    publicPath: '/'
  },
  module: {
    loaders: [
      {
        test: /\.js$/,
        loader: 'babel-loader',
        exclude: /node_modules/,
        query: {
          presets: ['react', 'es2015']
        }
      }
    ]
  }
}

什麼是source map

5.在client資料夾中新增client.js

import React from 'react';
import ReactDOM from 'react-dom';
import App from '../components/App';

ReactDOM.render(
<App/>,document.getElementById('app')
)

<App/>即為我們的react元件

6.在components資料夾中新增App.js

此即為我們第一個react元件

import React, { Component } from 'react'

class App extends Component {
  render() {
    return <div>I'm Banana!</div>
  }
}

export default App

之後輸入webpack --config webpack.config.js 會自動產生dist資料夾，裡面包含bundle.js檔案，此為webpack打包後的東西

之後於terminal輸入，npm run serve(寫在package.json中的scripts內)

執行伺服器，並打開瀏覽器輸入開啟localhost:3000

下載React devtool

https://chrome.google.com/webstore/detail/react-developer-tools/fmkadmapgofadopljbjfkapdkoienihi

之後chrome devtool的tab會多一個React

讓我們不用重新整理網頁

在package.json內加入

1.不用重新整理網頁 (讓我們不用使用webpack-dev-server也有-hot的指令)

"webpack-hot-middleware": "*"

2.讓hot middleware知道react的class

"babel-preset-react-hmre": "*",

以及讓webpack跑在我們架設的express server上

"webpack-dev-middleware": "*"

使用指令

npm install --save webpack-hot-middleware babel-preset-react-hmre webpack-dev-middleware

來安裝以上三個package

接著更改剛才server資料夾下的 server.js

var express = require('express');
var path = require('path');
var config = require('../webpack.config.js');
var webpack = require('webpack');
var webpackDevMiddleware = require('webpack-dev-middleware');
var webpackHotMiddleware = require('webpack-hot-middleware');

var app = express();

var compiler = webpack(config);

app.use(webpackDevMiddleware(compiler, {noInfo: true, publicPath: config.output.publicPath}));
app.use(webpackHotMiddleware(compiler));

app.use(express.static('./dist'));

app.use('/', function (req, res) {
  res.sendFile(path.resolve('client/index.html'));
});

var port = 3000;

app.listen(port, function(error) {
  if (error) throw error;
  console.log("Express server listening on port", port);
});

現在我們可以直接用server.js去compile 我們的webpack config檔案，不用再輸入指令compile

最後因為我們剛才有用hot middle所以我們可以使用--hot去讓他自動reload網頁，但我們不想在指令輸入，所以可以把他加在webpack config內

webpack.config.js

var webpack = require('webpack');

module.exports = {
  devtool: 'inline-source-map',
  entry: [
    'webpack-hot-middleware/client',
    './client/client.js'
  ],
  output: {
    path: require("path").resolve("./dist"),
    filename: 'bundle.js',
    publicPath: '/'
  },
  plugins: [
    new webpack.optimize.OccurrenceOrderPlugin(),
    new webpack.HotModuleReplacementPlugin(),
  ],
  module: {
    loaders: [
      {
        test: /\.js$/,
        loader: 'babel-loader',
        exclude: /node_modules/,
        query: {
          presets: ['react', 'es2015', 'react-hmre']
        }
      }
    ]
  }
}

現在執行 npm run serve

再去更改app.js內的字，可以看到不用重新啟動伺服器，也不用按網頁的重新整理，即可更新

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