JavaScript has several types of objects, including built-in objects like Math and Date, host objects provided by the ECMAScript6, and user-defined objects created by developers.
In JavaScript, there are several types of objects, including:
- Built-in Objects:
- Global objects: like
Math,Date,JSON. - Fundamental objects: like
Object,String,Number,Boolean,Symbol. - Error objects: like
Error,SyntaxError,TypeError,ReferenceError, and others.
- Global objects: like
- Host Objects:
- Provided by the environment, such as a web browser or Node.js environment.
- Examples:
window,document,XMLHttpRequest,console, and others.
- User-defined Objects:
- Created by the developer, using
Object,Function,Array, orclasskeyword.
- Created by the developer, using
All JavaScript objects have a prototype property that allows them to inherit properties and methods from other objects.
Types of objects in JavaScript example
Simple example code.
<!DOCTYPE html>
<html>
<body>
<script>
// Global objects
console.log(Math.PI);
console.log(new Date());
console.log(JSON.parse('{"name":"John", "age":30}'));
// Fundamental objects
var person = {name: "John", age: 30};
console.log(typeof person);
var str = "Hello, World!";
console.log(typeof str);
var num = 42;
console.log(typeof num);
var bool = true;
console.log(typeof bool);
var sym = Symbol("foo");
console.log(typeof sym);
// User-defined Objects
function Car(make, model, year) {
this.make = make;
this.model = model;
this.year = year;
}
Car.prototype.getMakeModelYear = function() {
return this.make + ' ' + this.model + ' ' + this.year;
}
var myCar = new Car("Honda", "Civic", 2022);
console.log(myCar.getMakeModelYear());
</script>
</body>
</html>Output:
Error objects: Error, SyntaxError, TypeError, ReferenceError, and others.
try {
var x = y + 1; // y is not defined
}
catch(err) {
console.log(err instanceof ReferenceError); // Output: true
}
Host Objects: Provided by the environment, such as a web browser or Node.js environment.
console.log(window.location.href); // Output: current URL
console.log(document.querySelector("h1").textContent); // Output: text content of the first <h1> element in the document
Comment if you have any doubts or suggestions on this JS object topic.
Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.
OS: Windows 10
Code: HTML 5 Version