Question 1

How do you implement a polyfill for bind in JavaScript?

Accepted Answer

Function.prototype.myBind = function(context, ...presetArgs) { const fn = this; return function(...laterArgs) { return fn.call(context, ...presetArgs, ...laterArgs); }; }.

Question 2

How do you support preset arguments in a bind polyfill?

Accepted Answer

Use rest parameters: myBind = function(context, ...presetArgs). Spread them in the call: fn.call(context, ...presetArgs, ...laterArgs). This merges preset and later arguments.

Question 3

How do you support new in a bind polyfill?

Accepted Answer

Check this instanceof boundFn. If true (called with new), use new fn(...args) instead of fn.call(context, ...args). Set boundFn.prototype = Object.create(fn.prototype).

Question 4

Why do you need to set boundFn.prototype in a bind polyfill?

Accepted Answer

So that instances created with new boundFn() have the correct prototype chain. Without it, instanceof checks would fail. Set boundFn.prototype = Object.create(fn.prototype).

How do you implement a polyfill for bind in JavaScript?

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