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How do you explicitly set a new property on `window` in TypeScript?

Asked 10 years ago
Viewed 516.71 k times

I setup global namespaces for my objects by explicitly setting a property on window.

window.MyNamespace = window.MyNamespace || {};

TypeScript underlines MyNamespace and complains that:

The property 'MyNamespace' does not exist on value of type 'window' any"

I can make the code work by declaring MyNamespace as an ambient variable and dropping the window explicitness but I don't want to do that.

declare var MyNamespace: any;

MyNamespace = MyNamespace || {};

How can I keep window in there and make TypeScript happy?

As a side note I find it especially funny that TypeScript complains since it tells me that window is of type any which by definitely can contain anything.

asked 10 years ago

Correct Answer

I just found the answer to this in another Stack Overflow question's answer.

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

window.MyNamespace = window.MyNamespace || {};

Basically, you need to extend the existing window interface to tell it about your new property.

answered 10 years ago

Other Answer

To keep it dynamic, just use:

(<any>window).MyNamespace

Note that this may not work with TSX because the compiler might think that the <any> is a TSX element. Check out this answer for type assertion that is compatible with TSX.

answered 1 year ago