Use of for and iin loops in JavaScript

Source: Internet
Author: User

A for In loop in JavaScript is typically used to traverse an array

The first thing to understand is what an array is, an array, which is actually a collection of a set of similar variables. Let's take a look at an array instance that holds a hobby:

<body>

<script type= "Text/javascript" >

var x;

var hobbies = new Array ();

Hobbies[0] = "JavaScript";

HOBBIES[1] = "CSS";

HOBBIES[2] = "basketball";

for (x in Hobbies)//each variable in the array

{

document.write (Hobbies[x] + "<br/>");

}

</script>

</body>

The output results are as follows:

Javascript

Css

Basketball

Let's analyze the above example:

The var hobbies = new Array ();

Hobbies[0] = "JavaScript"; and the next two sentences are assigned to the hobbies array. This is not the same as the variables we've seen before, hobbies a "[0]", which is the index of the variable. As we've already said, arrays are sets of variables, so we need to specify which variable in the array to assign to before assigning a value. Here, "[0]" means the first variable contained in the hobbies array, and yes, the index of the array is starting at 0, which may be a bit awkward at first, and slowly get used to it.

The last for In loop is well understood,

for (x in Hobbies)//each variable in the array

{

document.write (Hobbies[x] + "<br/>");

}

Represents all the variables that traverse the hobbies array and outputs them individually.

Related Article

E-Commerce Solutions

Leverage the same tools powering the Alibaba Ecosystem

Learn more >

Apsara Conference 2019

The Rise of Data Intelligence, September 25th - 27th, Hangzhou, China

Learn more >

Alibaba Cloud Free Trial

Learn and experience the power of Alibaba Cloud with a free trial worth $300-1200 USD

Learn more >

Contact Us

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.