Common Mistakes with call, apply, and bind

Common Mistakes with call, apply, and bind

Mistake 1: Confusing call and apply Arguments

call takes comma-separated args. apply takes an array. Mixing them up is common.

Mistake 2: Expecting bind to Invoke

bind returns a function. You must call it separately. fn.bind(obj) does nothing until you call the result.

Mistake 3: Trying to Re-bind

bound.bind(newObj) does not change this. The first bind wins.

Mistake 4: Using bind on Arrow Functions

Arrows ignore bind. this is lexical and cannot be changed.

Mistake 5: Forgetting to Pass this as First Argument

fn.call(5, 10) sets this to 5 (a primitive, boxed to Number) and passes 10 as the first arg. Usually, you want fn.call(obj, 5, 10).

The Takeaway

Mistakes: confusing call (comma) and apply (array) args, expecting bind to invoke (it returns a function), trying to re-bind (first bind wins), using bind on arrows (ignored), and forgetting this as the first argument. Know the differences clearly.