错误：纱线启动 - 错误命令“start”未找到

Question

yarn run v1.22.4 error Command "start" not found. info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

This error comes up after I type yarn start in command prompt... The main problem is there is no 'scripts' in package.json..

can anyone help please?

Answer 1

Here's an example package.json from one of my reactjs projects.
Depending on what environment/framework you work on, you are probably looking for the scripts object as defined below.

{
  "name": "bitmex-dashboard",
  "version": "0.1.0",
  "private": true,
  "dependencies": {
    "@testing-library/jest-dom": "^4.2.4",
    "@testing-library/react": "^9.3.2",
    "@testing-library/user-event": "^7.1.2",
    "@types/jest": "^24.0.0",
    "@types/node": "^12.0.0",
    "@types/react": "^16.9.41",
    "@types/react-dom": "^16.9.8",
    "axios": "^0.19.2",
    "bitmex-realtime-api": "^0.4.3",
    "form-data": "^3.0.0",
    "lodash": "^4.17.15",
    "react": "^16.13.1",
    "react-dom": "^16.13.1",
    "react-redux": "^7.2.0",
    "react-scripts": "3.4.1",
    "react-tradingview-widget": "^1.3.2",
    "redux": "^4.0.5",
    "redux-logger": "^3.0.6",
    "redux-saga": "^1.1.3",
    "semantic-ui-react": "^0.88.2",
    "typescript": "~3.7.2",
    "ws": "^7.3.1"
  },
  "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build",
    "test": "react-scripts test",
    "eject": "react-scripts eject"
  },
  "eslintConfig": {
    "extends": "react-app"
  },
  "browserslist": {
    "production": [
      ">0.2%",
      "not dead",
      "not op_mini all"
    ],
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version"
    ]
  },
  "devDependencies": {
    "@types/lodash": "^4.14.157",
    "@types/react-redux": "^7.1.9",
    "@types/redux-logger": "^3.0.8",
    "@types/socket.io-client": "^1.4.33",
    "@types/ws": "^7.2.6",
    "redux-devtools-extension": "^2.13.8"
  }
}

If you are using nodejs, you want something like this:

...
"scripts":{
  "start": "node index.js"
....
}

Here's a brief explanation on package.json

Answer 2

If you are creating a new react project, you may want to use create-react-app as it handles all the initial configurations and installs all the required dependencies too

https://reactjs.org/docs/create-a-new-react-app.html#create-react-app

Answer 3

When you write some code in a .js file you execute the content of that file passing it are argument in your terminal || shell to node command like this

Here I presume you have a file which is named index.js

node ./index.js 

So instead of having to type this command every time you can add a script property in your package.json file so it will reference that command every time you execute in your terminal npm run start || npm startnpm run start || npm start or yarn start if you are using Yarn .

This will look like this

// package.json
{
   "scripts": {
       "start": "node ./index.js",
   } 
}

Generaly you specify the entry point where you application execution must start.

You can learn more about package.json file here Creating a package.json file and The package.json guide