Learn JavaScript

JavaScript for in Loop

JavaScript for in Loop is used to loop through the properties of an object. In each iteration, one property of the object is assign to the variable. The process of such assignment continues until all properties of the object get exhausted.

Standard Syntax of JavaScript for in Loop

for (variable in object)
{
Statement 1;
Statement 2;
Statement 3;
.
.
.
Statement n;
}

Example

<html>
<body>
<h2>Program to understand the working of for in loop</h2>
<script>
var user = {name: "Johney", age: 18, tutorial: "JavaScript", cd: 7};
var detail = "";
var x
for(x in user)
{
detail += user[x] + "<br>";
}
document.write(detail);
</script>
</body>
</html>

Output

Program to understand the working of for in loop

Johney
18
JavaScript
7

Note: It is recommended not to use JavaScript for in loop through arrays, where the index order is important. In that case it is advisable to use for loop, instead.


Audience

This JavaScript tutorial is designed to help the beginners as well as the professional developers. For better understanding the language of the tutorial is kept simple and easy to understand.

Prerequisites

This tutorial demands to have the basic knowledge of the programming languages such as c or c++, HTML, and objects for the better understanding of the JavaScript programming language. The other basic requirement to learn JavaScript through this tutorial is the basic knowledge of computer and information technology so you can easily acquire a better understanding JavaScript programming.

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