JavaScript this Keyword

The JavaScript this Keyword

The JavaScript this keyword refers to the object it belongs to.

It has different values depending on where it is used:

In a method, this refers to the owner object.
Alone, this refers to the global object.
In a function, this refers to the global object.
In a function, in strict mode, this is undefined.
In an event, this refers to the element that received the event.
Methods like call(), and apply() can refer this to any object.

Example

var person = {
firstName: "John",
  lastName : "Doe",
id       : 5566,
fullName : function() {
    return this.firstName + " " + this.lastName;
  }
};

Explicit Function Binding

The call() and apply() methods are predefined JavaScript methods.

They can both be used to call an object method with another object as an argument.

You can read more about call() and apply() later in this tutorial.

Example

var person1 = {
fullName: function() {
    return this.firstName + " " + this.lastName;
  }
}
var person2 = {
firstName:"John",
lastName: "Doe",
}
person1.fullName.call(person2);  // Will return "John Doe"

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JavaScript this Keyword JAVASCRIPT

JavaScript this Keyword