JavaScript Object Methods
Example
const person = {
firstName: "John",
lastName: "Doe",
id: 5566,
fullName: function() {
return this.firstName + " " +
this.lastName;
}
};
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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:
If you access the fullName property, without (), it will return the function definition:
Adding a Method to an Object
Adding a new method to an object is easy:
Example
person.name = function () {
return this.firstName + " " + this.lastName;
};
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Using Built-In Methods
This example uses the toUpperCase() method of the String object, to convert a text
to uppercase:
let message = "Hello world!";
let x = message.toUpperCase();
The value of x, after execution of the code above will be:
HELLO WORLD!
Example
person.name = function () {
return (this.firstName + " " + this.lastName).toUpperCase();
};
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