What are the call, apply, and bind methods used for in JavaScript?

call, apply, and bind are used to control the execution context (the value of this) of a function and to pass arguments.

• call: Calls a function with a specified this value and arguments passed separately.

  const person = { name: 'Alice' };
  
  function greet(greeting, punctuation) {
    console.log(`${greeting}, ${this.name}${punctuation}`);
  }
  
  greet.call(person, 'Hello', '!'); // Output: Hello, Alice!
  

• apply: Calls a function with a specified this value and arguments passed as an array (or array-like object).

  const person = { name: 'Bob' };
  
  function greet(greeting, punctuation) {
    console.log(`${greeting}, ${this.name}${punctuation}`);
  }
  
  greet.apply(person, ['Hi', '.']); // Output: Hi, Bob.
  

• bind: Creates a new function that, when called, has its this keyword set to the provided value, with a given sequence of arguments preceding any provided when the new function is called. The function itself is not called immediately.

  const person = { name: 'Charlie' };
  
  function greet(greeting, punctuation) {
    console.log(`${greeting}, ${this.name}${punctuation}`);
  }
  
  const boundGreet = greet.bind(person, 'Yo');
  
  boundGreet('?'); // Output: Yo, Charlie?
  boundGreet('!'); // Output: Yo, Charlie!
  

Comparison table:

Method	Arguments Passing	Return Value	Call Type
call	Separately	Result of the function execution	Immediate call
apply	Array	Result of the function execution	Immediate call
bind	Separately	New function with bound context	Creates a function, not called immediately