Saturday, November 30, 2019

Steps on how to implement JavaScript Nested functions with examples


Hello guys! afternoon to you all and welcome to my tutorial post on JavaScript. In my last tutorial post i talked about how to implement JavaScript functions in your program. So now we are going to be discussing about another interesting topic on JavaScript called JavaScript Nested functions.

Prior to JavaScript 1.2, function definition was allowed only in top level global code, but JavaScript 1.2 allows function definitions to be nested within other functions as well. Still there is a restriction that function definition may not appear within loops or conditionals. These restrictions on function definitions apply only to function declarations with the function statement.

As we will discuss later in my next tutorial post, function literals (another feature introduced in JavaScript 1.2) may appear within any JavaScript expression, which means that they  can appear within if and other statements.

You can also read our tutorial post on: JavaScript - Loop Control

Example

Try the following example below to learn how to implement nested functions.

<html>
     <head>
          <script  type="text/javascript">
               <!--
                    function  hypotenuse(a , b)  {
                         function  square(x)  {
                              return  x*x;
                         }
                         return  Math . sqrt(square(a) + square(b));    
                    }
                    function  secondFunction()  {
                         var  result; 
                         result = hypotenuse(1 , 2);
                         document.write(result);
                    }
               //-->
          </script>
     </head>

     <body>
          <p>Click the following button to call the function</p>
          <form>
               <input  type="button"  onclick="secondFunction()"  value="Click">    
          </form>
     </body>
</html>


You can also read our tutorial post on: JavaScript Operators

Output

Below is the output of the above example:

Click the following button to call the function 

  

Alright guys we have come to the end of this tutorial post on JavaScript nested functions. Always feel free to ask your questions via the comment box below.

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