1.

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

Answer»

1. 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: "Sandy"};

sayHello.call(obj);

// Returns "Hello Sandy"

  • 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: "John"};
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: "John"};
saySomething.apply(person4, ["awesome"]);

2. bind():


  • This method returns a new function, where the value of “this” keyword 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: "Vivek"};

var detailsOfPerson1 = bikeDetails.displayDetails.bind(person1, "TS0122", "Bullet");

// Binds the displayDetails function to the person1 object


detailsOfPerson1();
// Returns Vivek, bike details: TS0452, Thunderbird


Discussion

No Comment Found

Related InterviewSolutions