JavaScript Object Methods

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JavaScript Object Methods
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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:

Example
name = person.fullName();
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If you access the fullName property, without (), it will return the function definition:

Example
name = person.fullName;
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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
Adding 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.

Now You Can Try:
myMother.changeName(“Doe”);
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JavaScript knows which person you are talking about by “substituting” this with myMother.

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