JavaScript Tutorials - Herong's Tutorial Examples - 2.33, by Herong Yang
Conditional "if" Statement Examples
This section provides a JavaScript tutorial example showing different types of 'if' statements.
To help you understand how "if" statements work, I wrote the following the JavaScript tutorial example, If_Statements.html:
<html>
<!-- If_Statements.html
Copyright (c) 2002 HerongYang.com. All Rights Reserved.
-->
<head><title>If Statements</title></head>
<body>
<pre>
<script type="text/javascript">
// Single-statement "if"
document.write('\n');
var is_january = true;
if (is_january) document.write("Happy New Year!\n");
// Multi-statement "if"
document.write('\n');
var is_log_on = true;
if (is_log_on) {
document.write("Open the log file.\n");
document.write("Write the log message.\n");
document.write("Close the log file.\n");
}
// "if ... else" statement
document.write('\n');
var is_admin = false;
if (is_admin) {
document.write("Display the delete button.\n");
document.write("Display the edit button.\n");
} else {
document.write("Display the view button.\n");
}
// "if ... else if" statement
document.write('\n');
var week_day = 4;
var open_hours;
if (week_day == 0) {
open_hours = "closed";
} else if (week_day >= 1 && week_day <= 5) {
open_hours = "open from 9:00am to 9:00pm";
} else if (week_day == 6) {
open_hours = "open from 9:00am to 5:00pm";
} else {
open_hours = "undefined";
}
document.write("The library is " + open_hours + ".\n");
</script>
</pre>
</body>
</html>
The output of this sample JavaScript is:
Happy New Year! Open the log file. Write the log message. Close the log file. Display the view button. The library is open from 9:00am to 9:00pm.
Table of Contents
ECMAScript Language Specification and JavaScript Dialects
Data Types, Variables and Expressions
►Conditional "if" Statement Examples
"switch ... case" Statement Example
"while" Loop Statement Example
Creating, Accessing, and Manipulating Arrays
Defining and Calling Functions
Web Browser Supporting JavaScript
Server-Side and Client-Side Web Scripting
Defining Your Own Object Types
Inheritance of Properties and Methods through the Prototype Object Chain
'jrunscript' - JavaScript Shell Command from JDK
Using Functions as "Function" Objects
Introduction to Built-in Object Types
W3C's Document Object Model (DOM) Specifications