运行 create-react-app 构建脚本时如何设置构建 .env 变量? [英] How to set build .env variables when running create-react-app build script?

问题描述

我在 create-react-app 中使用以下环境变量:

I'm using the following environment variable in my create-react-app:

console.log(process.env.REACT_APP_API_URL) // http://localhost:5555

它在我通过读取 .env 文件运行 npm start 时起作用:

It works when I run npm start by reading a .env file:

REACT_APP_API_URL=http://localhost:5555

如何在执行 npm run build 时设置不同的值，例如 http://localhost:1234?

How do I set a different value like http://localhost:1234 when executing a npm run build?

这是我的 package.json 文件:

{
  "name": "webapp",
  "version": "0.1.0",
  "private": true,
  "devDependencies": {
    "react-scripts": "0.9.0"
  },
  "dependencies": {
    "react": "^15.4.2",
    "react-dom": "^15.4.2"
  },
  "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build",
    "test": "react-scripts test --env=jsdom",
    "eject": "react-scripts eject"
  }
}

推荐答案

你可以像这样使用process.env.NODE_ENV:

const apiUrl = process.env.NODE_ENV === 'production' ? process.env.REACT_APP_PROD_API_URL : process.env.REACT_APP_DEV_API_URL;

您需要设置 REACT_APP_PROD_API_URL 和 REACT_APP_DEV_API_URL.

或者，如果生产 URL 始终相同，您可以简化它:

Or, if the production URL is always the same, you could simplify it:

const apiUrl = process.env.NODE_ENV === 'production' ? 'https://example.com' : process.env.REACT_APP_DEV_API_URL;

Create React App 在构建时将 NODE_ENV 设置为生产"，因此您无需担心何时将其设置为生产.

Create React App sets the NODE_ENV to 'production' for you on build, so you don't need to worry about when to set it to production.

注意:您必须重新启动服务器(例如再次运行 npm start)以检测环境变量更改.

Note: you must restart your server (e.g. run npm start again) to detect environment variable changes.

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