JavaScript – Variables, Naming Rules, and Syntax

Variables and Naming Rules

1. JavaScript variables can be used to hold values [e.g.: (x=10) or expression (a=b+c)]. 
2. Variable can have short names (like x and y) or more descriptive names (age, sum total volume) 
3. JavaScript variables are declared using the keyword var. 

Rule For Naming Variables

1. Variable names must begin with a letter. 
2. Variable names can also begin with $ and _. 
3. Variable names are case sensitive ( Y and y are different variables). 
4. Both JavaScript statements and JavaScript variables are case-sensitive.

You declare JavaScript variables with the var keyword. When you assign a numeric value to a variable, do not put quotes around the value. When you assign a text value to a variable, put double or single quotes around the value.

JS Code

<script type="text/javascript">
 var case1;
 var case2;
 var case3;
</script>

From the above example we already knew that variables in JavaScript are generally declared inside the <script> tags.

Multiple Variable Declaration

JS Code

<script type="text/javascript">
 var case1,case2,case3;
</script>

Variable initialization can be done in two ways:

• At the time of variable declaration
• At the later point when the variable is required

JS Code

<script type="text/javascript">
 var case1="harish";
 var case2="satya";
 var case3;
 case3=2000;
</script>