将 dotenv 与 React 和 Webpack 结合使用

Question

我正在寻找可以将 dotenv 与 React 结合使用的信息

import React from "react"
console.log(process.env.REACT_APP_API_KEY)

.env但是，当我在我的方向的根目录中创建文件时，我undefined在控制台中收到一条消息。

我应该注意，我没有使用react-create-app。

这是我的.env文件

REACT_APP_API_KEY=secretKey

这是我的 webpack 配置文件。

有什么方法可以使用 dotenv 而不使用 node.js 和创建小型服务器。

const currentTask = process.env.npm_lifecycle_event;
const path = require("path");
const { CleanWebpackPlugin } = require("clean-webpack-plugin");
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
const { postcss } = require("postcss-mixins");
const HtmlWebpackPlugin = require("html-webpack-plugin");
const fse = require("fs-extra");

const postCSSPlugins = [
  require("postcss-import"),
  require("postcss-mixins"),
  require("postcss-simple-vars"),
  require("postcss-nested"),
  require("postcss-hexrgba"),
  require("autoprefixer")
];

class RunAfterCompile {
  apply(compiler) {
    compiler.hooks.done.tap("Copy images", function () {
      fse.copySync("./app/assets/images", "./docs/assets/images");
    });
  }
}

let cssConfig = {
  test: /\.css$/i,
  use: [
    "css-loader?url=false",
    { loader: "postcss-loader", options: { plugins: postCSSPlugins } }
  ]
};

let pages = fse
  .readdirSync("./app")
  .filter(function (file) {
    return file.endsWith(".html");
  })
  .map(function (page) {
    return new HtmlWebpackPlugin({
      filename: page,
      template: `./app/${page}`
    });
  });

let config = {
  entry: "./app/assets/scripts/App.js",
  plugins: pages,
  module: {
    rules: [
      cssConfig,
      {
        test: /\.js$/,
        exclude: /(node_modules)/,
        use: {
          loader: "babel-loader",
          options: {
            presets: ["@babel/preset-react", "@babel/preset-env"],
            plugins: ["@babel/plugin-transform-runtime"]
          }
        }
      }
    ]
  }
};

if (currentTask == "dev") {
  cssConfig.use.unshift("style-loader");
  config.output = {
    filename: "bundled.js",
    path: path.resolve(__dirname, "app")
  };
  config.devServer = {
    before: function (app, server) {
      server._watch("./app/**/*.html");
    },
    contentBase: path.join(__dirname, "app"),
    hot: true,
    port: 3000,
    host: "0.0.0.0",
    historyApiFallback: { index: "/" }
  };
  config.mode = "development";
}

if (currentTask == "build") {
  cssConfig.use.unshift(MiniCssExtractPlugin.loader);
  postCSSPlugins.push(require("cssnano"));
  config.output = {
    filename: "[name].[chunkhash].js",
    chunkFilename: "[name].[chunkhash].js",
    path: path.resolve(__dirname, "docs")
  };
  config.mode = "production";
  config.optimization = {
    splitChunks: { chunks: "all" }
  };
  config.plugins.push(
    new CleanWebpackPlugin(),
    new MiniCssExtractPlugin({ filename: "styles.[chunkhash].css" }),
    new RunAfterCompile()
  );
}

module.exports = config;

我已经在这里呆了几个小时了，但我似乎无法在网上找到我需要的东西。希望有人以前遇到过这个问题。

谢谢

Answer 1

有一个dotenv-webpack插件专门针对这种情况。

设置非常简单：

// webpack.config.js
const dotEnv = require('dotenv-webpack')
module.exports = {
  plugins: [new dotEnv()]
}

文档

编辑

这个答案对于评论来说太冗长了：

您添加了dotEnv错误的plugins属性。

 module: {
    rules: [
      cssConfig,
      {
        test: /\.js$/,
        exclude: /(node_modules)/,
        use: {
          loader: "babel-loader",
          options: {
            presets: ["@babel/preset-react", "@babel/preset-env"],
            plugins: [/* WRONG */ new dotEnv(), "@babel/plugin-transform-runtime"]
          }
        }
      }
    ]
  }

什么时候应该在这里添加：

if (currentTask == "dev") {
  config.plugins = [/* RIGHT */ new dotEnv()]
}