The developers can use the following primitive datatypes in their web application or Windows store application.
– String
– Boolean
– Numbers
JavaScript also support null and undefined.
The variables are like containers that can hold data . The data can be accessed by specifying the variable name. The variable in JavaScript are declared using var keyword. The developers can initialize the variable with a value either during the variable initialization or later in the program.
Below is a sample program demonstrating the usage of variables of various datatypes in JavaScript.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>Ginktage.com Home Page</title>
<script language="javascript" type="text/javascript">
var TutorialName = "Ginktage.com - Learn JavaScript";
var Salary = 10000.50;
</script>
</head>
<body>
</body>
</html>
The var keyword has a purpose . Javascript language is kind of untyped language . You don’t have to specify the type of variable during the declaration . Javascript takes care of the type automatically based on the values assigned.
The JavaScript variable can either have a Global scope or local scope . A global scoped variable is accessible everywhere in your javascript file but a local scoped variable is only visible within the function where it is defined.
Below is a sample code snippet demonstrating the Global scope and local scope variable.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>Ginktage.com Home Page</title>
<script type="text/javascript">
var Variable1 = "Ginkatge.com"; // Global Variable
function checkscope() {
var Variable1 = "Google.com"; // Local Variable
}
</script>
</head>
<body>
</body>
</html>
There are some rules to be followed when declaring a variable in JavaScript.
- The variable name should not have any reserved keyword of JavaScript.
- The variable name should not start with a number . It should begin with a letter or underscore . Also note that it is case sensitive.
- Eg : _Test1 is a valid variable name.
