YouTipJs This
# JavaScript this Keyword
In object-oriented languages, `this` represents a reference to the current object.
However, in JavaScript, `this` is not fixed; it changes according to the execution context.
* In a method, `this` refers to the object that owns the method.
* If used 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
```javascript
var person = {
firstName: "John",
lastName : "Doe",
id : 5566,
fullName : function() {
return this.firstName + " " + this.lastName;
}
};
[Try it Yourself »](#)
* * *
## this in a Method
In an object method, `this` refers to the object that "owns" the method.
In the example above, `this` represents the `person` object.
The `fullName` method belongs to the `person` object.
## Example
```javascript
fullName : function() {
return this.firstName + " " + this.lastName;
}
[Try it Yourself »](#)
* * *
## this Alone
When used alone, `this` refers to the global (Global) object.
In a browser, the global object is `window`:
## Example
```javascript
var x = this;
[Try it Yourself »](#)
In strict mode, if used alone, `this` also refers to the global (Global) object.
## Example
```javascript
"use strict";
var x = this;
[Try it Yourself »](#)
* * *
## this in a Function (Default)
In a function, the owner of the function is the default binding for `this`.
In a browser, the global object is `window`:
## Example
```javascript
function myFunction() {
return this;
}
[Try it Yourself »](#)
* * *
## this in a Function (Strict Mode)
In strict mode, functions are not bound to `this`, so `this` is `undefined`.
## Example
```javascript
"use strict";
function myFunction() {
return this;
}
[Try it Yourself »](#)
* * *
## this in Event Handlers
In HTML event handlers, `this` refers to the HTML element that received the event:
## Example
[Try it Yourself »](#)
* * *
## Object Method Binding
In the following example, `this` is the `person` object, because `person` owns the `fullName` function.
## Example
```javascript
var person = {
firstName : "John",
lastName : "Doe",
id : 5566,
myFunction : function() {
return this;
}
};
[Try it Yourself »](#)
## Example
```javascript
var person = {
firstName: "John",
lastName : "Doe",
id : 5566,
fullName : function() {
return this.firstName + " " + this.lastName;
}
};