Add Constructor<T> to lib.es5.d.ts

[mlhaufe]

Search Terms

Constructor, utility type, lib.es5.d.ts

Suggestion

The following type should be added to lib.es5.d.ts:

type Constructor<T> = new (...args: any[]) => T

Use Cases

This is a common pattern used in mixins and other class oriented declarations:

This also complements the existing utility types:

Examples

type Constructor<T> = new(...args: any[]) => T;

function Tagged<T extends Constructor<{}>>(Base: T) {
    return class extends Base {
        _tag: string;
        constructor(...args: any[]) {
            super(...args);
            this._tag = "";
        }
    }
}

const TaggedPoint = Tagged(Point);

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.

[MartinJohns]

Duplicate of #20256.

[typescript-bot]

This issue has been marked as a 'Duplicate' and has seen no recent activity. It has been automatically closed for house-keeping purposes.