TypeScript error: Property 'X' does not exist on type 'Window'

Question

I have added TS to my React/Redux app.

I use window object in my app like this:

componentDidMount() {
  let FB = window.FB;
}

TS throws an error:

TypeScript error: Property 'FB' does not exist on type 'Window'. TS2339

I want to fix the error.

1 (doesn't work)

// Why doesn't this work? I have defined a type locally

type Window = {
  FB: any
}

componentDidMount() {
  let FB = window.FB;
}

// TypeScript error: Property 'FB' does not exist on type 'Window'. TS2339

2 (fixes the error)

I found the answer here https://stackoverflow.com/a/56402425/1114926

declare const window: any;

componentDidMount() {
  let FB = window.FB;
}
// No errors, works well

Why doesn't the first version work, but the second does, even though I do not specify FB property at all?

Answer 1

Why does declare const window: any; work?

Because you declare a local variable of type any. Having something of type any essentially turns off type checking for window so you can do anything with it. I really do not recommend this solution, it is a really bad one.

Why doesn't type Window = { FB: any } work? You define a type Window. This type if defined in a module has nothing to do with the type of the global window object, it is just a type that happens to be called Window inside your module.

The good solution To extend window you must extend the global Window interface. You can do this like this:

declare global {
    interface Window {
        FB:any;
    }
}

let FB = window.FB; // ok now

Note that this extension is going to be available in your whole project not just the file you define it in. Also if FB has definitions you might consider typing it a bit better (FB: typeof import('FBOrWhateverModuleNameThisHas'))

Answer 2

There are a few ways to solve this problem.

Some examples:

1-) Do a cast

(window as any).X

2-) Put the following code in a file named react-app-env.d.ts

interface Window {
  X?: {
    Y?: {
      .......
    }
  }
}

Answer 3

you can solve the problem easily without any need to declaration

window["FB"]

UPDATE
since it's a workaround without any compiler configuration to ensure your program's compatibility with typescript maybe you will need just a type validation.

if(window["FB"]) {
  // do some FB logic
}

Answer 4

I use this without declare global

declare const window: Window &
   typeof globalThis & {
     FB: any
   }

Answer 5

HACK SOLUTION for problem "Property does not exist on type Window in TypeScript"

STEP:1 In your src directory, create a types directory that contains the following index.d.ts file: src/types/index.d.ts

export {};

declare global {
  interface Window {
    example: string; // whatever type you want to give. (any,number,float etc)
  }
}

STEP: 2 add the path to your types directory to your tsconfig.json file.

tsconfig.json

{
  "compilerOptions": {
    // ... rest
    "typeRoots": ["./node_modules/@types", "./src/types"]
  }
}

STEP: 3 Now use it, whereever you want to do it.

window.example = 'hello';

console.log(window.example);

Answer 6

I was facing this issue in my angular code. Below solution helped me to resolve the issue.

I resolved this error by creating a folder name types inside src and inside that folder created index.d.ts file.

the index.d.ts file will have below code.

export {};
declare global {
  interface Window {
    chrome: any;  // this will be your variable name
  }
}

If the error persists, try adding the path to your types directory to your tsconfig.json file.

{
  "compilerOptions": {
    // ... rest
    "typeRoots": ["./node_modules/@types", "./src/types"]
  }
}

Answer 7

better still

declare global {
  interface Window {
    FB: {
      CustomerChat: {
        hide: () => void;
        show: () => void;
      };
    };
  }
}

Answer 8

it should be ignored by creating global.d.ts file in root of project with this content:

export { }
declare global {
    interface Window {
        [key: string]: any 
    }
}

it ignores all variables of window object

Answer 9

This worked for me without declaring it globally

declare const window: Window &
   typeof globalThis & {
     FB: any
   }

This was the error I was facing Error: Property 'name' does not exist on type '{}'.ts(2339) Although mine wasn't really related with your code but this guide should help you

Answer 10

For anyone coming from Next.Js, you need to use <Script /> inside of <body> to load it (loading it inside of the <Head /> won't work):

https://nextjs.org/docs/basic-features/script

Answer 11

Use a temp variable and cast it to any

const tempWindow: any = window;
const anyProperty = tempWindow.anyProperty;