Explain call(), apply() and, bind() methods

 call()

It’s a predefined method in javascript.

This method invokes a method (function) by specifying the owner object.

Example 1:

function sayHello(){
  return "Hello " + this.name;
}
        
var obj = {name: "Vijay"};
        
sayHello.call(obj);
        
// Returns "Hello Vijay"
          

call() method allows an object to use the method (function) of another object.

Example 2:

var person = {
  age: 23,
  getAge: function(){
    return this.age;
  }
}
        
var person2 = {age:  54};
person.getAge.call(person2);
        
// Returns 54  

call() accepts arguments:

function saySomething(message){
  return this.name + " is " + message;
}
        
var person4 = {name:  "Vijay"};
        
saySomething.call(person4, "awesome");
// Returns "John is awesome"    

apply()

The apply method is similar to the call() method. The only difference is that,

call() method takes arguments separately whereas, apply() method takes arguments as an array.

function saySomething(message){
  return this.name + " is " + message;
}
        
var person4 = {name:  "Vijay"};
        
saySomething.apply(person4, ["awesome"]);

bind()

This method returns a new function, where the value of “this” skeyword will be bound to the owner object, which is provided as a parameter.

Example with arguments:

var bikeDetails = {
    displayDetails: function(registrationNumber,brandName){
    return this.name+ " , "+ "bike details: "+ registrationNumber + " , " + brandName;
  }
}
        
var person1 = {name:  "Vijay"};
        
var detailsOfPerson1 = bikeDetails.displayDetails.bind(person1, "TS0122", "Bullet");
        
// Binds the displayDetails function to the person1 object
        
        
detailsOfPerson1();
// Returns Vijay, bike details: TS0452, Thunderbird