javascript-data-types

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JavaScript Data Types

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String, Number, Boolean, Array, Object, Null, Undefined.

JavaScript Has Dynamic Types

JavaScript has dynamic types. This means that the same variable can be used as different types:
Example:

var x;               // Now x is undefined
var x = 5;           // Now x is a Number
var x = "John";      // Now x is a String

A string is a variable which stores a series of characters like "Compuhelp".
A string can be any text inside quotes. You can use single or double quotes:

var carname="Compuhelp YM50";
var carname='Compuhelp YM50';

<!DOCTYPE html>
<html>
<body>
<script>
var carname1="Compuhelp YM50";
var carname2='Compuhelp YM50';
var answer1="It's alright";
var answer2="He is called 'Compu'";
var answer3='He is called "help"';
document.write(carname1 + "<br>")
document.write(carname2 + "<br>")
document.write(answer1 + "<br>")
document.write(answer2 + "<br>")
document.write(answer3 + "<br>")
</script>
</body>
</html>

Output:

JavaScript Numbers:

JavaScript has only one type of numbers. Numbers can be written with, or without decimals:
Example:

var x1=34.00;      // Written with decimals
var x2=34;         // Written without decimals

JavaScript Booleans:

Booleans can only have two values: true or false.
Example:

var x=true; 
var y=false;

JavaScript Arrays:

The following code creates an Array called Computer:
Example:

var cars=new Array(); 
cars[0]="Keyboard"; 
cars[1]="mouse"; 
cars[2]="CPU";

var cars=new Array("Keyboard","Mouse","CPU");

JavaScript Objects

An object is delimited by curly braces. Inside the braces the object's properties are defined as name and value pairs (name : value). The properties are separated by commas:
Example:

var person={firstname:"John", lastname:"Doe", id:5566};