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 variable 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>