TypeScript · Middle · Question 40 of 75

How do you extend the type of the global `Window` object from a module?

export {};
declare global {
  interface Window { dataLayer: unknown[] }
}

✓Correct answer: With declare global and merging into the Window interface
2With window.dataLayer = [] - the type is inferred automatically
3With type Window = Window & { dataLayer: unknown[] }

Explanation

In a module file (with import/export), global declarations go inside declare global. The Window interface merges with your extension. Redeclaring type Window causes a duplicate identifier error.

How do you extend the type of the global `Window` object from a module?

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How do you extend the type of the global Window object from a module?

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Test yourself

How do you extend the type of the global `Window` object from a module?