Introduction:

I am going to explain you the functionality of for in loop, because for-in loop is a little more different from other loops.

In Java Script there is another loop which is known as For-in Loop. It is used to loop through properties of an object. There are various objects like Navigator objects and Window objects which I will be explaining later on. These objects contain various properties which can be easily accessed using. The example given below gives an idea about what is for-in loop and why it is used.

Syntax of for-in Loop:
for (variable in object)
{
         Code to be executed
}
Example:
<html xmlns="http://www.w3.org/1999/xhtml">

<head>
</head>
<body>
    <script type="text/javascript"><!--
        var WinProperty;
        document.write("Window Object Properties Names<br /> ");
        for (WinProperty in window) {
            document.write(WinProperty);
            document.write("<br />");
        }
        document.write("Exiting from the loop!");
-->     </script>
</body>
</html>

It list out various properties of Window object. In similar way we can list of other object properties.  In each iteration one property of an object is assigned in a variable WinProperty. Till all of the property is not accessed and assigned to the variable the for-in loop will continue executing and printing the property name on the screen.

                This loop differs from the for loop, that for loop does not work on objects

 Output:

java script for loop

Conclusion:

In this article I explained the concept of for-in loop and how it works, how it differs from for loop.


  Modified On Nov-30-2017 12:52:44 AM

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