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window.opener should not be typed as any #49415
Description
Activity
window.openeris still declared asanyin both TypeScript 4.7.3 and the current native compiler. The browser API may returnnull(and otherwise exposes the opener window proxy), soanyloses the nullability and prevents useful checking.type IsAny<T> = 0 extends 1 & T ? true : false; type Assert<T extends true> = T; // Expected: The DOM declaration gives window.opener a specific non-any type. // Actual: typeof window.opener is any. type OpenerIsAny = Assert<IsAny<typeof window.opener>>;
The assertion currently succeeds; it should fail after
window.openerreceives a specific DOM type.- linked a pull request that will close this issueType `window.opener` as nullable `WindowProxy` #64212
on Sep 9, 2026
lib Update Request
Configuration Check
My compilation target is
esnextand my lib is["ESNext", "dom"].Missing / Incorrect Definition
window.openershould not be typed asany. I might be missing something obvious, but this has already been reported and supposedly fixed at #42433 more than a year ago, but it still seems to be typed asany, both on my local version of Typescript (version 4.7.3) and at https://github.com/microsoft/TypeScript/blob/main/lib/lib.dom.d.ts#L17209