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call(), apply(), bind()

Medium

In plain terms

call and apply invoke a function with a specific this and arguments. call takes args individually; apply takes an array. bind returns a new function with this and optional args pre-set.

What you need to know

  • •call(thisArg, ...args)
  • •apply(thisArg, [args])
  • •bind(thisArg, ...args) returns function

Try it yourself

Copy the code below and run it in your browser console or a code editor:

function greet(greeting, punctuation) {
  return greeting + ', ' + this.name + punctuation;
}

const person = { name: 'Alice' };

greet.call(person, 'Hello', '!');   // "Hello, Alice!"
greet.apply(person, ['Hi', '.']);   // "Hi, Alice."

const boundGreet = greet.bind(person, 'Hey');
boundGreet('!');  // "Hey, Alice!"

// bind for event handlers
this.handleClick = this.handleClick.bind(this);

Learn more

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