Build error for WeakRef Class

[jamesgjt]

Hi,

I use create-react-app to create the app for me, and I have create some js file that use the WeakRef class in my react app.
When I run npm start command, it is running fine and able to compile.
However, when I run npm run build for the project. the eslint compiler failed to compile with error message WeakRef is not defined

Anyone encounter this behavior?

[NourMoftah]

WeakRef is a built-in JavaScript global (ES2021), so the error is usually caused by ESLint not recognizing it rather than React itself.

A few things to check:

1. Make sure your environment supports WeakRef (Node.js 14.6+ and modern browsers).
2. Update your ESLint configuration to use a modern ECMAScript version, for example:

{
  "parserOptions": {
    "ecmaVersion": 2021
  },
  "env": {
    "es2021": true
  }
}

3.If you're using create-react-app, ensure you're on the latest react-scripts version, as older ESLint configurations may not recognize newer globals.

If the problem only occurs during npm run build, please share:

Your react-scripts version
Your Node.js version
Any custom ESLint configuration (.eslintrc or eslintConfig in package.json)