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What is the difference between call, apply, and bind?

All three control `this`; they differ in invocation timing and argument passing.

Ideal Answer

call, apply, and bind are methods on Function.prototype that let you set the this value of a function.

Method Invokes immediately? Arguments
call Yes Comma-separated
apply Yes Array or array-like
bind No — returns a new function Optional preset args
JavaScript 
function greet(greeting, punctuation) {
  return `${greeting}, ${this.name}${punctuation}`
}

const user = { name: 'Ada' }

greet.call(user, 'Hello', '!')       // "Hello, Ada!"
greet.apply(user, ['Hello', '!'])      // "Hello, Ada!"
const sayHi = greet.bind(user, 'Hi')
sayHi('?')                           // "Hi, Ada?"

When to use each

  • call / apply — borrow a method or invoke immediately with a specific this.
  • bind — create a permanently bound callback (e.g. event handlers, partial application).

Mnemonic: Call = Comma-separated args; Apply = Array of args.