JavaScript Tutorial || JavaScript Variable

author
January 27, 2024

JavaScript Variable


JavaScript variables are containers for storing data values
There are two types of variables in JavaScript : local variable and global variable.

example, x, y, and z, are variables

var x = 5;
var y = 6;
var z = x + y;

x stores the value 8
y stores the value 2
z stores the value 10

1.Before you use a variable in a JavaScript program, you must declare it. Variables are declared with     the var keyword
2.Name must start with a letter (a to z or A to Z), underscore( _ ), or dollar( $ ) sign
3.JavaScript variables are case sensitive, for example b and B are different variables
4.Global Variables −  It can be defined anywhere in your JavaScript code.
5.Local Variables − A local variable will be visible only within a function where it is defined. 

Global Variables

It is accessible from any function. A variable i.e. declared outside the function or declared with window object is known as global variable. For example

<html>
   <body onload = findvalue();>   
      <script type = "text/javascript">
        
            var xvalue = "global";    
            
         
      </script>     
   </body>
</html>

Local Variables

local variable will be declared only within a block or function. It is accessible within the function or block only. For example:

<html>
   <body onload = findvalue();>   
      <script type = "text/javascript">
        
           
            function findvalue( ) {
               var xvalue = "local";   
               document.write(xvalue );
            }
         
      </script>     
   </body>
</html>