JavaScript Methods
JavaScript methods are the 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 create an object method with the following syntax:
methodName : function() { code lines }
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:
If you access the fullName property, without (), it will return the function definition:
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();
The value of x, after execution of the code above will be:
HELLO WORLD!
Adding New Methods
Defining methods to an object is done inside the constructor function:
Example
function person(firstName, lastName, age, eyeColor) {
this.firstName = firstName;
this.lastName = lastName;
this.age = age;
this.eyeColor = eyeColor;
this.changeName = function (name) {
this.lastName = name;
};
}
The changeName() function assigns the value of name to the person's lastName property.
JavaScript knows which person you are talking about by "substituting" this with myMother.