W3Schools.com


  
HOME HTML CSS XML JAVASCRIPT ASP PHP SQL MORE... REFERENCES | EXAMPLES | FORUM | ABOUT
BEST WEB HOSTING JustHosts

JavaScript If...Else Statements

« Previous Next Chapter »

Conditional statements are used to perform different actions based on different conditions.


Conditional Statements

Very often when you write code, you want to perform different actions for different decisions. You can use conditional statements in your code to do this.

In JavaScript we have the following conditional statements:

  • if statement - use this statement to execute some code only if a specified condition is true
  • if...else statement - use this statement to execute some code if the condition is true and another code if the condition is false
  • if...else if....else statement - use this statement to select one of many blocks of code to be executed
  • switch statement - use this statement to select one of many blocks of code to be executed

If Statement

Use the if statement to execute some code only if a specified condition is true.

Syntax

if (condition)
  {
  code to be executed if condition is true
  }

Note that if is written in lowercase letters. Using uppercase letters (IF) will generate a JavaScript error!

Example

<script type="text/javascript">
//Write a "Good morning" greeting if
//the time is less than 10

var d=new Date();
var time=d.getHours();

if (time<10)
  {
  document.write("<b>Good morning</b>");
  }
</script>

Try it yourself »

Notice that there is no ..else.. in this syntax. You tell the browser to execute some code only if the specified condition is true.


If...else Statement

Use the if....else statement to execute some code if a condition is true and another code if the condition is not true.

Syntax

if (condition)
  {
  code to be executed if condition is true
  }
else
  {
  code to be executed if condition is not true
  }

Example

<script type="text/javascript">
//If the time is less than 10, you will get a "Good morning" greeting.
//Otherwise you will get a "Good day" greeting.

var d = new Date();
var time = d.getHours();

if (time < 10)
  {
  document.write("Good morning!");
  }
else
  {
  document.write("Good day!");
  }
</script>

Try it yourself »


If...else if...else Statement

Use the if....else if...else statement to select one of several blocks of code to be executed.

Syntax

if (condition1)
  {
  code to be executed if condition1 is true
  }
else if (condition2)
  {
  code to be executed if condition2 is true
  }
else
  {
  code to be executed if condition1 and condition2 are not true
  }

Example

<script type="text/javascript">
var d = new Date()
var time = d.getHours()
if (time<10)
  {
  document.write("<b>Good morning</b>");
  }
else if (time>10 && time<16)
  {
  document.write("<b>Good day</b>");
  }
else
  {
  document.write("<b>Hello World!</b>");
  }
</script>

Try it yourself »


Examples

More Examples

Random link
This example demonstrates a link, when you click on the link it will take you to W3Schools.com OR to RefsnesData.no. There is a 50% chance for each of them.


« Previous Next Chapter »

Free Online Website Builder - No Downloading Needed

Create a free Flash website with our simple, online web design editing platform. Stunning templates and user-friendly tools make website building easy and fun.

Start Creating your free website now!


Altova® XMLSpy® - The industry's leading XML editor!

Altova XMLSpy

Whether you're new to XML or already an advanced user, the user-friendly views and powerful entry helpers, wizards, and debuggers in XMLSpy are designed to meet your XML and Web development needs from start to finish. New features in Version 2011!

  • XML editor
  • Graphical XML Schema / DTD editors
  • XSLT 1.0/2.0 editor, debugger, profiler
  • XQuery editor, debugger, profiler
  • XBRL validator, taxonomy editor, taxonomy wizard
  • New! Chart creation for XML data
  • Support for Office Open XML (OOXML)
  • Graphical WSDL 1.1/2.0 editor & SOAP debugger
  • JSON editing & conversion
  • Java, C#, C++ code generation
  • 32-bit and 64-bit versions
  • And much more!

Download a free trial today!

  Altova XMLSpy

 

W3Schools Certification

W3Schools' Online Certification

The perfect solution for professionals who need to balance work, family, and career building.

More than 6000 certificates already issued!

Get Your Certificate »

The HTML Certificate documents your knowledge of HTML.

The CSS Certificate documents your knowledge of advanced CSS.

The JavaScript Certificate documents your knowledge of JavaScript and HTML DOM.

The jQuery Certificate documents your knowledge of jQuery.

The XML Certificate documents your knowledge of XML, XML DOM and XSLT.

The ASP Certificate documents your knowledge of ASP, SQL, and ADO.

The PHP Certificate documents your knowledge of PHP and SQL (MySQL).

WEB HOSTING
Best Web Hosting
PHP MySQL Hosting
Top 10 Web Hosting
UK Reseller Hosting
Web Hosting
Top Web Hosting
$1 Domain Sale
WEB BUILDING
Download XML Editor
FREE Flash Website
6,000+ HTML Templates
Download now (FREE)
Advertise on Google
Stand out on Google search and maps Click Here
W3SCHOOLS EXAMS
Get Certified in:
HTML, CSS, JavaScript, XML, PHP, and ASP
W3SCHOOLS BOOKS
New Books:
HTML, CSS
JavaScript, and Ajax
STATISTICS
Browser Statistics
Browser OS
Browser Display
SHARE THIS PAGE