What is the difference between closure and nested functions in JavaScript?

JavascriptWeb DevelopmentFront End Technology

JavaScript Closures

In JavaScript, all functions work like closures. A closure is a function, which uses the scope in which it was declared when invoked. It is not the scope in which it was invoked.

Here’s an example

Live Demo

<!DOCTYPEhtml>
<html>
   <body>
      <h2>JavaScriptClosures</h2>
         <script>
            varp = 20;
            functiona(){
               var p = 40;
               b(function(){
                  alert(p);
            });
         }
         functionb(f){
            var p = 60;
            f();
         }
         a();
      </script>
   </body>
</html>

JavaScript nested functions

JavaScript 1.2 allows function definitions to be nested within other functions as well.Still, there is a restriction that function definitions may not appear within loops or conditionals. These restrictions on function definitions apply only to function declarations with the function statement.

Example

You can try to run the following example to learn how to implement nested functions

Live Demo

<html>
   <head>
      <script>
         <!--
            functionhypotenuse(a,b) {
               functionsquare(x){returnx*x;}
               returnMath.sqrt(square(a)+square(b));
            }
           
            functionsecondFunction() {
               varresult;
               result=hypotenuse(5,4);
               document.write(result );
            }
         //-->
      </script>
   </head>
   <body>
      <p>Clickthe following button to call the function</p>
      <form>
         <inputtype="button"onclick="secondFunction()"value="CallFunction">
      </form>
      <p>Usedifferent parameters inside the function and then try...</p>
   </body>
</html>
raja
Published on 25-Jan-2018 11:09:26
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