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JavaScript•Objects, Classes, and Advanced Patterns

JavaScript this Keyword

Flash cards

Review the key moves

1/4

Core idea

What is the main idea behind JavaScript this Keyword?

Lesson checks

Practice each idea before moving on

Short Mimo-style checks built from this lesson's code, terms, and sequence.

1Quick choice

Which statement best captures the main point of this lesson?

2Fill blank

Complete the missing token from the example code.

___ person = {

3Order

Put the learning moves in the order that makes the concept easiest to apply.

The this keyword refers to an object.

this in a Function

this in an Object Method

this in Objects

The this keyword refers to an object.

In JavaScript, this is used to access the object that is calling a method.

this in an Object Method

When used inside an object method, this refers to the object.

Example

const person = {
  firstName: "John", lastName: "Doe", age: 50, fullName: function() {
    return this.firstName + " " + this.lastName;
  }
};

In the example above

this.firstName refers to the firstName property of the person object
this.lastName refers to the lastName property of the person object

Why Use this ?

The this keyword makes it possible to use the same method with different objects.

Example

const person1 = {
  name: "John", hello: function() {
    return "Hello " + this.name;
  }
};
const person2 = {
  name: "Anna", hello: function() {
    return "Hello " + this.name;
  }
};
document.getElementById("demo").innerHTML = person1.hello();

this Alone

When used alone, this refers to the global object.

In a browser, the global object is the window object.

Example

let x = this;
document.getElementById("demo").innerHTML = x;

In strict mode, this is undefined when used alone.

this in a Function

In a regular function, this also refers to the global object.

Example

function myFunction() {
  return this;
}
document.getElementById("demo").innerHTML = myFunction();

Summary

In an object method, this refers to the object
this lets methods access object properties
Used alone, this refers to the global object

JavaScript this Keyword

Flash cards

Review the key moves

1/4

Core idea

What is the main idea behind JavaScript this Keyword?

Lesson checks

Practice each idea before moving on

Short Mimo-style checks built from this lesson's code, terms, and sequence.

1Quick choice

Which statement best captures the main point of this lesson?

2Fill blank

Complete the missing token from the example code.

___ person = {

3Order

Put the learning moves in the order that makes the concept easiest to apply.

The this keyword refers to an object.

this in a Function

this in an Object Method

this in Objects

The this keyword refers to an object.

In JavaScript, this is used to access the object that is calling a method.

this in an Object Method

When used inside an object method, this refers to the object.

Example

const person = {
  firstName: "John", lastName: "Doe", age: 50, fullName: function() {
    return this.firstName + " " + this.lastName;
  }
};

In the example above

this.firstName refers to the firstName property of the person object
this.lastName refers to the lastName property of the person object

Why Use this ?

The this keyword makes it possible to use the same method with different objects.

Example

const person1 = {
  name: "John", hello: function() {
    return "Hello " + this.name;
  }
};
const person2 = {
  name: "Anna", hello: function() {
    return "Hello " + this.name;
  }
};
document.getElementById("demo").innerHTML = person1.hello();

this Alone

When used alone, this refers to the global object.

In a browser, the global object is the window object.

Example

let x = this;
document.getElementById("demo").innerHTML = x;

In strict mode, this is undefined when used alone.

this in a Function

In a regular function, this also refers to the global object.

Example

function myFunction() {
  return this;
}
document.getElementById("demo").innerHTML = myFunction();

Summary

In an object method, this refers to the object
this lets methods access object properties
Used alone, this refers to the global object