bind.ts

bind.ts

Function.prototype.bind with typings for TypeScript

Function#bind is untyped in TypeScript (in v2.3 at least, cf: #212). TypeScript always returns any for bind().

function foo(a: number, b: number): string {
    return `${this.msg}: ${a + b}`;
}
// bar is `any`!
const bar = foo.bind({msg: 'hello'}, 10);
// ok
bar(20); // 'hello: 30'
// should be a type error, but actually allowed...
bar('anything');

bind.ts is a workaround for this issue.

import bind from 'bind.ts';

// bar is `(b: number) => string`
const bar = bind(foo, {msg: 'hello'}, 10);
// ok
bar(20); // 'hello: 30'
// error!
bar('anything');

Limitation

The maximum number of arguments of the function is 5.

License

MIT License: Teppei Sato <[e-mail]>