通过DefinePlugin使用Webpack传递NODE_ENV值

Question

我试图NODE_ENV使用webpackvia 将值注入我的代码中DefinePlugin.我或多或少地检查了一个相同的问题,但仍无法使其工作.

具体来说,这是我的设置.

在package.json:

"scripts": {
    "build": "rimraf dist && cross-env NODE_ENV=production webpack",
    "dev": "cross-env NODE_ENV=development && node webpack-dev-server.js"
},

在webpack.config.js:

"use strict";

/* requiring the modules */
const webpack = require("webpack");
const path = require("path");

/* defining the source and distribution paths */
const DIST_DIR = path.resolve(__dirname, "dist");
const SRC_DIR = path.resolve(__dirname, "src");

const DEVELOPMENT = process.env.NODE_ENV === "development";
const PRODUCTION = process.env.NODE_ENV === "production";
// const PRODUCTION = !!process.argv.find((element) => element === '--production');
// const DEVELOPMENT = !!process.argv.find((element) => element === '--development');


/* defining the entries*/
const productionEntries = {
    home: SRC_DIR + "/_home.js",
    about: SRC_DIR + "/_about.js",
};
const developmentEntries = Object.assign({}, productionEntries, {webpackDevServer: ["webpack/hot/dev-server", "webpack-dev-server/client?http://localhost:8080"]});
const entries = PRODUCTION ? productionEntries : developmentEntries;


/* defining the output */
const output = {
    filename: "[name].js",
    path: DIST_DIR,
    publicPath: "/dist/",
    pathinfo: true,
    library: "MyLibraryName"
};


/* defining the plugins */
const plugins = PRODUCTION
    ? [
        new webpack.optimize.OccurrenceOrderPlugin(),
        new webpack.optimize.AggressiveMergingPlugin(),
        new webpack.optimize.UglifyJsPlugin({comments: false}),
    ]
    :  [
        new webpack.HotModuleReplacementPlugin(),
    ];

plugins.push(
    new webpack.optimize.CommonsChunkPlugin({name: "vendor.bundle", minChunks: 2}),
    new webpack.DefinePlugin({
        PRODUCTION: PRODUCTION,
        DEVELOPMENT: DEVELOPMENT,
    })
);


/* defining the modules -> rules -> loaders */
const modules = {
    rules:
        [
            {
                test: /\.(js|jsx)$/,
                include: SRC_DIR,
                exclude: /node_modules/,
                loader: "babel-loader",
                options:
                    {
                        presets: ["react", ["es2015", {modules: false}], "stage-2"]
                    }
            }
        ]
};



/* building the webpack config object */
const config = {
    entry: entries,
    output: output,
    module: modules,
    plugins: plugins,
    devtool: "source-map",
    target: "web",
    stats: "verbose"
};

/* exporting the webpack config */
module.exports = config;

最后,_about.js我有以下内容:

// output after using: npm run dev
console.log(process.env.NODE_ENV); // prints undefined
console.log(PRODUCTION); // prints false
console.log(DEVELOPMENT); // prints false

if (module.hot) {
    module.hot.accept();
}

问题:

• 由于npm run dev成功运行(即,服务器启动并且插件和条目被选中),我不明白为什么输出console.log(DEVELOPMENT)是false,以及为什么console.log(process.env.NODE_ENV)打印undefined.
• 在内部执行的条件检查中webpack.config.js,NODE_ENV正确选取值,否则插件,条目和开发服务器将无法正常工作.但是,我无法将该值传递给_about.js使用DefinePlugin.
• 我也尝试过EnvironmentPlugin,同样的结果.

我的问题:请你帮我理解事情的发生地点吗？

---

编辑1:

我尝试了以下没有任何改进:

new webpack.DefinePlugin({
    PRODUCTION: JSON.stringify(PRODUCTION),
    DEVELOPMENT: JSON.stringify(DEVELOPMENT)
})

我正在node.js上Windows 10.

---

编辑2:

尝试:

const DEVELOPMENT = process.env.NODE_ENV === "development";
const PRODUCTION = process.env.NODE_ENV === "production";

// with this inside plugins:
new webpack.DefinePlugin({
    "process.env.PRODUCTION": JSON.stringify(PRODUCTION),
    "process.env.DEVELOPMENT": JSON.stringify(DEVELOPMENT)
})

和(使用npm run dev)我得到以下输出:

console.log(process.env.PRODUCTION); // false
console.log(process.env.DEVELOPMENT); // false
console.log(process.env.NODE_ENV); // undefined
console.log(PRODUCTION); // Uncaught ReferenceError: PRODUCTION is not defined
console.log(DEVELOPMENT); // Uncaught ReferenceError: DEVELOPMENT is not defined

不幸的是没有改进.

---

编辑3:

我devDependencies是:

"devDependencies": {
    "babel-core": "^6.21.0",
    "babel-loader": "^6.2.10",
    "babel-preset-es2015": "^6.18.0",
    "babel-preset-react": "^6.16.0",
    "babel-preset-stage-2": "^6.18.0",
    "cross-env": "^3.1.4",
    "rimraf": "^2.5.4",
    "webpack": "^2.2.0-rc.4",
    "webpack-dev-server": "^2.2.0-rc.0"
}

---

编辑4 :(已解决)

@Cleiton发现了这个问题.它与npm脚本的构建方式有关cross-env.请参阅下面的完整答案.

Answer 1

问题是因为你使用cross-env的方式不对.它只更改其上下文的env变量,所以当你使用'&&'来运行webpack时,它已经消失了,webpack什么都没看到.

所以你必须写

"scripts": {
    "build": "rimraf dist && cross-env NODE_ENV=production webpack",
    "dev": "cross-env NODE_ENV=development node webpack-dev-server.js"
},

请注意,您已为"构建"脚本编写了权利.

另一个问题是如果你想在你的代码库中引用"process.env.PRODUCTION",你应该写:

   new webpack.DefinePlugin({
        "process.env.PRODUCTION": JSON.stringify(PRODUCTION),
        "proccess.env.DEVELOPMENT": JSON.stringify(DEVELOPMENT),
    });