What is the difference between call, apply and bind?

All three let you control this for a normal function. The difference is whether the function runs now and how arguments are supplied.

function introduce(greeting, punctuation) {
  return greeting + ", " + this.name + punctuation;
}

const asha = { name: "Asha" };

introduce.call(asha, "Hi", "!"); // "Hi, Asha!"
introduce.apply(asha, ["Hello", "."]); // "Hello, Asha."

const bound = introduce.bind(asha, "Hey");
bound("?"); // "Hey, Asha?"

The differences

• call(thisArg, arg1, arg2) invokes immediately with individual arguments
• apply(thisArg, [arg1, arg2]) invokes immediately with an array-like argument list
• bind(thisArg, arg1) returns a new function and does not invoke it
• Bound arguments are prepended to the arguments supplied later

bind is useful when passing a method as a callback, because the receiver is preserved even when the callback is called by another system.

class Counter {
  count = 0;

  increment() {
    this.count += 1;
  }
}

const counter = new Counter();
const increment = counter.increment.bind(counter);

setTimeout(() => {
  increment();
  console.log(counter.count); // 1
}, 0);