在CREATE REACT APP中使用环境变量的步骤(不含dotenv包)

Create a new file called .env in the root folder of the project (NOT inside src folder but one level up. Remember, it should be at the same level as package.json (THIS IS VERY IMPORTANT!!) Define your variables like so (Note that every variable you define should start with REACT_APP_) Example : .env file REACT_APP_ACCESS_KEY=8Sh9ZLwZevicWC-f_lmHvvyMu44cg3yZBU Note: You don't have to enclose the value in "" or '' Now you can use the variable in any of your components like so const apiKey = process.env.REACT_APP_ACCESS_KEY The name should match the key given in the .env file Now before you try this out, always remember to restart the local server. Once you run npm start it works. This step applies whenever you make changes to the .env file. We generally forget this step so it might not work. Optionally, check if .env entry is present in .gitignore file. If the entry of .env exists in .gitignore then your .env file will not be pushed to github(This is the reason why we use .env in the first place).

Install dotenv as devDependencies: npm i --save-dev dotenv Create a .env file in the root directory: my-react-app/ |- node-modules/ |- public/ |- src/ |- .env |- .gitignore |- package.json |- package.lock.json. |- README.md Update the .env file like below & REACT_APP_ is the compulsory prefix for the variable name. REACT_APP_BASE_URL=http://localhost:8000 REACT_APP_API_KEY=YOUR-API-KEY [ Optional but Good Practice ] Now you can create a configuration file to store the variables and export the variable so can use it from others file. For example, I've create a file named base.js and update it like below: export const BASE_URL = process.env.REACT_APP_BASE_URL; export const API_KEY = process.env.REACT_APP_API_KEY; Or you can simply just call the environment variable in your JS file in the following way: process.env.REACT_APP_BASE_URL

Webpack用户

如果你正在使用Webpack，你可以安装和使用dotenv-webpack插件。要做到这一点，请遵循以下步骤:

安装包

yarn add dotenv-webpack

创建一个.env文件

// .env
API_KEY='my secret api key'

将它添加到webpack.config.js文件中:

// webpack.config.js
const Dotenv = require('dotenv-webpack');

module.exports = {
  ...
  plugins: [
    new Dotenv()
  ]
  ...
};

在代码中使用它

process.env.API_KEY

有关更多信息和配置信息，请访问dotenv-webpack。

设置好环境变量后，必须再次运行npm start。这就是我所缺少的部分。在自动重新加载时，.env变量不会更新。

你必须安装npm install env-cmd

在根目录中创建.env并像这样更新& REACT_APP_是变量名的强制前缀。

REACT_APP_NODE_ENV="production"
REACT_APP_DB="http://localhost:5000"

更新package.json

  "scripts": {
    "start": "env-cmd react-scripts start",
    "build": "env-cmd react-scripts build",
    "test": "react-scripts test",
    "eject": "react-scripts eject"
  }

现在有一种更简单的方法。

只需创建.env。在根目录中的本地文件，并在那里设置变量。在你的情况下:

REACT_APP_API_KEY = 'my-secret-api-key'

然后在JavaScript文件中以如下方式调用它:

process.env.REACT_APP_API_KEY

React从react-scripts@0.5.0开始支持环境变量。你不需要一个外部包来做到这一点。

在.env中添加开发环境变量

*注:我建议使用。env。Local而不是.env，因为create-react-app在创建项目时将此文件添加到gitignore。

文件的优先级:

npm start: .env.development.local， .env.development， .envlocal /, .env

NPM运行build: . environment .production。地方,.env。生产、.env。地方、.env

NPM测试:.env.test。地方,.env。Test， .env(注意。env。本地不见了)

更多信息:添加自定义环境变量