W3Schools
home HOME Tutorials | References | Examples | Forum | About
Search W3Schools :

JS Basic
JS HOME
JS Introduction
JS How To
JS Where To
JS Statements
JS Comments
JS Variables
JS Operators
JS Comparisons
JS If...Else
JS Switch
JS Popup Boxes
JS Functions
JS For Loop
JS While Loop
JS Break Loops
JS For...In
JS Events
JS Try...Catch
JS Throw
JS onerror
JS Special Text
JS Guidelines

JS Objects
JS Objects Intro
JS String
JS Date
JS Array
JS Boolean
JS Math
JS RegExp
JS HTML DOM

JS Advanced
JS Browser
JS Cookies
JS Validation
JS Animation
JS Image Maps
JS Timing
JS Create Object
JS Summary

Examples/Quiz
JS Examples
JS Object Examples
JS DOM Examples
JS Quiz
JS Exam

JS References
JS Objects
JS HTML DOM

Selected Reading
Web Statistics
Web Glossary
Web Hosting
Web Quality

W3Schools Tutorials
W3Schools Forum

Helping W3Schools

JavaScript Comments

previous next

JavaScript comments can be used to make the code more readable.


JavaScript Comments

Comments can be added to explain the JavaScript, or to make it more readable.

Single line comments start with //.

This example uses single line comments to explain the code:

<script type="text/javascript">
// This will write a header:
document.write("<h1>This is a header</h1>");
// This will write two paragraphs:
document.write("<p>This is a paragraph</p>");
document.write("<p>This is another paragraph</p>");
</script>

Try it yourself.


JavaScript Multi-Line Comments

Multi line comments start with /* and end with */.

This example uses a multi line comment to explain the code:

<script type="text/javascript">
/*
The code below will write
one header and two paragraphs
*/
document.write("<h1>This is a header</h1>");
document.write("<p>This is a paragraph</p>");
document.write("<p>This is another paragraph</p>");
</script>

Try it yourself.


Using Comments to Prevent Execution

In this example the comment is used to prevent the execution of a single code line:

<script type="text/javascript">
document.write("<h1>This is a header</h1>");
document.write("<p>This is a paragraph</p>");
//document.write("<p>This is another paragraph</p>");
</script>

Try it yourself.

In this example the comments is used to prevent the execution of multiple code lines:

<script type="text/javascript">
/*
document.write("<h1>This is a header</h1>");
document.write("<p>This is a paragraph</p>");
document.write("<p>This is another paragraph</p>");
*/
</script>

Try it yourself.


Using Comments at the End of a Line

In this example the comment is placed at the end of a line:

<script type="text/javascript">
document.write("Hello"); // This will write "Hello" 
document.write("Dolly"); // This will write "Dolly" 
</script>


previous next


The tools you need to build your web project!

Instant Demo

Ektron CMS400.NET Version 7.6 delivers all of the flexibility and features you need to deploy the Web site you want, quickly and efficiently.

learn more...

 

 

 

6 ways to take your site to the next level with Ektron:

Social Networking Create site stickiness through social networking. Keep it personal, relevant and interactive and they'll come back for more.
Open API Keep it open. Your site needs to be ready and able to connect to outside services. Ektron's open API gives you maximum flexibility.
Document Management Streamline content and document management. Users need to quickly and intuitively find and add information.
Content Authors Empower your content authors. Reduce IT bottlenecks by allowing business users to create and edit Web content and forms.
Taxonomy Climb to the top of search rankings. SEO tools, URL aliasing and eCommerce for your digital marketing strategy
Web 2.0 Tools Add powerful Web 2.0 tools like blogs, wikis, forums, geo-mapping, rating systems and RSS feeds easily.
See why there are 20,000+ Ektron integrations worldwide.
Request an INSTANT DEMO or download a FREE TRIAL today.


Jump to: Top of Page or HOME or Printer Friendly Printer friendly page

W3Schools provides material for training only. We do not warrant the correctness of its contents. The risk from using it lies entirely with the user. While using this site, you agree to have read and accepted our terms of use and privacy policy.

Copyright 1999-2008 by Refsnes Data. All Rights Reserved.

Validate Validate W3C-WAI level A conformance icon W3Schools was converted to XHTML in December 1999
IISProtect
Password Protect
Your Web Pages
WEB HOSTING
$15 Domain Name
Registration
Save $20 / year!
Buy UK Domain Names
Register Domain Names
Cheap Domain Names
Cheap Web Hosting
Best Web Hosting
PHP MySQL Hosting
Top 10 Web Hosting
UK Reseller Hosting
Web Hosting
WEB BUILDING
Website Templates
Flash Templates
Website Builder
Internet Business Opportunity
Custom Programming
FREE Trial or Demo
Web Content Manager
Forms,Web Alerts,RSS
Download XML editor
Free Flash Website
EDUCATION
US Web Design Schools
HTML Exam