JavaScript Data Types:-
JavaScript variables:-
-
String
-
Number
-
Boolean
-
Array
-
object
1. String:-
A string is a sequence of letters, numbers, special characters and arithmetic values or combination of all. Strings can be created by enclosing the string literal (i.e. string characters) either within single quotes ('
) or double quotes ("
), as shown in the example below:
<!DOC TYPE HTML>
<HTML Lang=”en”>
<head>
<meta char set=”utf-8″>
<title>Creating Strings in JavaScript</title>
</head>
<body>
<script>
// Creating variables
var my String = ‘Hello World!’; // Single quoted string
var my String = “Hello World!”; // Double quoted string
// Printing variable values
document.write(my String + “<br>”);
document.write(my String);
</script>
</body>
</HTML>
Result:-Hello World!
Hello World!
2. Number:-
The Number is a primitive data type in JavaScript. Number type represents integer, float, hexadecimal, octal or exponential value. First character in a Number type must be an integer value and it must not be enclosed in quotation marks.
Example: Number in JavaScript
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Numbers</h2>
<p>Numbers can be written with, or without decimals:</p>
<p id=”demo”></p>
<script>
var x1 = 34.00;
var x2 = 34;
var x3 = 3.14;
document.getElementById(“demo”).innerHTML =
x1 + “<br>” + x2 + “<br>” + x3;
</script>
</body>
</html>
Result:-JavaScript Numbers
Numbers can be written with, or without decimals:
34
34
3.14
3. Boolean:-
Boolean can only have two values: true
or false
.
Example
<!DOCTYPE html>
<html>
<body><h2>JavaScript Booleans</h2><p>Booleans can have two values: true or false:</p><p id=”demo”></p><script>
var x = 5;
var y = 5;
var z = 6;
document.getElementById(“demo”).innerHTML =
(x == y) + “<br>” + (x == z);
</script>
</body>
</html>
Result:-
JavaScript BooleansBooleans can have two values: true or false:
true
false
4. Array:-
JavaScript arrays are written with square brackets.
Array items are separated by commas.
The following code declares (creates) an array called cars
, containing three items (car names):
Example
<!DOCTYPE html>
<html>
<body><h2>JavaScript Arrays</h2><p>Array indexes are zero-based, which means the first item is [0].</p><p id=”demo”></p><script>
var cars = [“Saab”,”Volvo”,”BMW”];
document.getElementById(“demo”).innerHTML = cars[0];
</script>
</body>
</html>
Result:-JavaScript ArraysArray indexes are zero-based, which means the first item is [0].
Saab
5. object:-
JavaScript objects are written with curly braces {}
.
Object properties are written as name:value pairs, separated by commas.
Example
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Objects</h2>
<p id=”demo”></p>
<script>
var person = {
firstName : “John”,
lastName : “Doe”,
age : 50,
eyeColor : “blue”
};
document.getElementById(“demo”).innerHTML =
person.firstName + ” is ” + person.age + ” years old.”;
</script>
</body>
</html
Result:-JavaScript Objects
John is 50 years old.