JavaScript – Variables, Naming Rules and Syntax

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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>

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