The answer
Basic: just sets this. Advanced: supports preset arguments (partial application) and the new operator (this is the new object when called with new, not the bound context).
How to Write a Polyfill for bind in JavaScript
What is the difference between the basic and advanced bind polyfill?
More FAQs in How to Write a Polyfill for bind in JavaScript
Function.prototype.myBind = function(context, ...presetArgs) { const fn = this; return function(...laterArgs) { return fn.call(context, ...presetArgs, ...laterArgs); }; }.
Use rest parameters: myBind = function(context, ...presetArgs). Spread them in the call: fn.call(context, ...presetArgs, ...laterArgs). This merges preset and later arguments.
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).
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