JavaScript Function Literals

JavaScript 1.2 introduces the concept of function literals which is another new way of defining functions. A function literal is an expression that defines an unnamed function.

Syntax

The syntax for a function literal is much like a function statement, except that it is used as an expression rather than a statement and no function name is required.

<script type = "text/javascript">
   <!--
      var variablename = function(Argument List) {
         Function Body 
      };
   //-->
</script>

Syntactically, you can specify a function name while creating a literal function as follows.

<script type = "text/javascript">
   <!--
      var variablename = function FunctionName(Argument List) {
         Function Body
      };
   //-->
</script>

But this name does not have any significance, so it is not worthwhile.

Example

Try the following example. It shows the usage of function literals.

Live Demo

<html>
   <head>
      <script type = "text/javascript">
         <!--
            var func = function(x,y) { 
               return x*y 
            };
            function secondFunction() {
               var result;
               result = func(10,20);
               document.write ( result );
            }
         //-->
      </script>
   </head>
   
   <body>
      <p>Click the following button to call the function</p>
      
      <form>
         <input type = "button" onclick = "secondFunction()" value = "Call Function">
      </form>
      
      <p>Use different parameters inside the function and then try...</p>
   </body>
</html>

Output

javascript_functions.htm