在Windows系统上安装React Project时遇到问题

Question

我正在尝试在Windows系统上安装React Web应用程序。之前它运行良好，但是当我重新安装Windows时，它停止了工作。我已经安装了Node和Npm。

当我运行命令npm install时，效果很好。但是，当我运行命令npm start时，它将引发以下错误：

未将REACT_APP_ENV识别为内部或外部命令

请同时参阅所附图像：

我为找到并解决此问题付出了很多努力，但没有任何效果。

这里是package.json文件的内容：

{
  "name": "wm-webapp",
  "version": "0.1.0",
  "private": true,
  "dependencies": {
    "axios": "^0.18.0",
    "gapi-client": "0.0.3",
    "libphonenumber-js": "^1.7.7",
    "moment": "^2.24.0",
    "node-sass": "^4.11.0",
    "react": "^16.7.0",
    "react-bootstrap": "^0.32.4",
    "react-dates": "^18.4.1",
    "react-dom": "^16.7.0",
    "react-facebook-login": "^4.1.1",
    "react-google-login": "^5.0.0",
    "react-places-autocomplete": "^7.2.0",
    "react-redux": "^5.0.7",
    "react-responsive": "^6.1.1",
    "react-router": "^4.3.1",
    "react-router-dom": "^4.3.1",
    "react-router-redux": "^5.0.0-alpha.9",
    "react-scripts": "2.1.3",
    "react-select": "^1.2.1",
    "react-stripe-elements": "^2.0.2",
    "react-table": "^6.8.6",
    "react-toastify": "^4.5.2",
    "redux": "^4.0.1",
    "redux-devtools-extension": "^2.13.7",
    "redux-form": "^8.1.0",
    "redux-form-input-masks": "^1.3.0",
    "redux-logger": "^3.0.6",
    "redux-saga": "^1.0.0",
    "redux-thunk": "^2.3.0",
    "store": "^2.0.12",
    "styled-components": "^4.1.3"
  },
  "scripts": {
    "start:env": "env-cmd .env.${REACT_APP_ENV} react-scripts start",
    "start": "REACT_APP_ENV=dev npm run start:env",
    "start:test": "REACT_APP_ENV=test npm run start:env",
    "build:env": "env-cmd .env.${REACT_APP_ENV} react-scripts build",
    "build": "REACT_APP_ENV=test npm run build:env",
    "build:prod": "REACT_APP_ENV=prod npm run build:env",
    "test": "react-scripts test",
    "eject": "react-scripts eject",
    "deploy": "aws s3 cp build s3://test.washmix.com/ --recursive --profile washmix",
    "format": "prettier --write --single-quote --tab-width=2 --print-width=80"
  },
  "eslintConfig": {
    "extends": "react-app"
  },
  "browserslist": [
    ">0.2%",
    "not dead",
    "not ie <= 11",
    "not op_mini all"
  ],
  "devDependencies": {
    "axios-mock-adapter": "^1.16.0",
    "env-cmd": "^8.0.2",
    "husky": "^1.3.1",
    "prettier": "^1.16.1"
  }
}

Answer 1

您必须将package.json中的所有环境变量更改为：

Set NAME_VARIABLE=VALUE 

Ex：

"start": "Set REACT_APP_ENV=dev&& npm run start:env",

Answer 2

已经迟到了，但是对于正在寻找答案的人们来说。

对于Windows（cmd.exe）：

'set "REACT_APP_ENV=dev" && npm run start'

对于Windows（Powershell）：

'($env:REACT_APP_ENV = "dev") -and (npm start)'

对于Linux，macOS（Bash）：

'REACT_APP_ENV=dev npm start'

您随时可以使用process.env.REACT_APP_ENV来获取事物变量。