Example #
var person = {
firstName: "John",
lastName : "Doe",
id : 5566,
fullName : function() {
return this.firstName + " " + this.lastName;
}
}; The this Keyword #
In a function definition, this refers to the “owner” of the function.
In the example above, this is the person object that “owns” the fullName function.
In other words, this.firstName means the firstName property of this object.
Read more about the this keyword at JS this Keyword.
JavaScript Methods #
JavaScript methods are actions that can be performed on objects.
A JavaScript method is a property containing a function definition.
| Property | Value |
|---|---|
| firstName | John |
| lastName | Doe |
| age | 50 |
| eyeColor | blue |
| fullName | function() {return this.firstName + ” ” + this.lastName;} |
Methods are functions stored as object properties.
Accessing Object Methods #
You access an object method with the following syntax:
objectName.methodName()
You will typically describe fullName() as a method of the person object, and fullName as a property.
The fullName property will execute (as a function) when it is invoked with ().
This example accesses the fullName() method of a person object:
Example #
name = person.fullName(); If you access the fullName property, without (), it will return the function definition:
Example #
name = person.fullName; Using Built-In Methods #
This example uses the toUpperCase() method of the String object, to convert a text to uppercase:
var message = "Hello world!";
var x = message.toUpperCase(); person.name = function () {
return this.firstName + " " + this.lastName;
}; 
