JS Variables and Data Types

JavaScript Variables and Data Types

JavaScript Data Types

In JavaScript there are the following types of data:

1. String data type. Are strings between apostrophes or quotation marks.
2. Numbers data type. Are data type integer or decimal.
3. Boolean data type. There are two boolean values: true and false.

JavaScript Variables

The variables are declared in JavaScript with the keyword var.

• In JavaScript is not required to declare a variable type. You need to write just the variable name. Variable type will be given after an assignment.

<script type="text/javascript">
<!--
var a;
var b;
//-->
</script>

• In JavaScript you can declare several variables in the same var, but the statements must be separated by commas.

<script type="text/javascript">
<!--
var a, b, c;
//-->
</script>

• When you declare a variable in JavaScript, you can assign an initial value the declared variable.

<script type="text/javascript">
<!--
var a = "Result";
var b;
b = 100;
document.write(a);
document.write("=");
document.write(b);
//-->
</script>

Result = 100

JavaScript Reserved Words:

These are JavaScript reserved words and can not be used as names of functions, objects or methods.