DOM suggestion: customisable `history.state` type

[OliverJAsh]

Search Terms

dom lib window state history any unknown

Suggestion

Currently window.history.state has type any. Could we provide a way for users to customise this type? Perhaps by making it generic or allowing the type to be changed through declaration merging.

Failing that, could we replace the any type with unknown, so we have type safety and users are forced to validate/widen the type?

Another possible solution: if TypeScript provided a way to override any types (https://github.com/microsoft/TypeScript/issues/4062, https://github.com/microsoft/TypeScript/issues/26188).

Also related:

• https://github.com/DefinitelyTyped/DefinitelyTyped/pull/41568
• https://github.com/DefinitelyTyped/DefinitelyTyped/pull/41580

Use Cases

Examples

Checklist

My suggestion meets these guidelines:

• [ ] This wouldn't be a breaking change in existing TypeScript/JavaScript code
• [ ] This wouldn't change the runtime behavior of existing JavaScript code
• [ ] This could be implemented without emitting different JS based on the types of the expressions
• [ ] This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.)
• [ ] This feature would agree with the rest of TypeScript's Design Goals.

[falsandtru]

Since history.state can be changed from anywhere, its type is unreliable. We have to validate history.state value each access. The value should be typed then.

[falsandtru]

Another code come from common libraries, other teams, or browser extensions may also use history.state.

https://github.com/defunkt/jquery-pjax/blob/master/jquery.pjax.js#L282-L293 https://github.com/falsandtru/pjax-api/blob/master/src/layer/data/store/state.ts

[OliverJAsh]

In that case it sounds like unknown is the best bet

[nmain100]

If taking that approach, this becomes a duplicate of https://github.com/microsoft/TypeScript/issues/26188