JavaScript Tutorials - Herong's Tutorial Examples - 2.33, by Herong Yang
Truncating and Iterating Array Elements
This section provides a tutorial example on how to use the array length to truncate and iterate over array elements.
As an object, an array has a special property called "length". You can use the object dot (.) operator to retrieve the length value: "array_name.length".
The array length property can be used to truncate an array by setting the "length" property to a lower value.
The array length property is also useful when you want to iterate all elements of an array.
For example, iterating all elements of an array with a "for" loop can be done as:
for (var i = 0; i < array_name.length; i++) { ... array_name[i]; }
Here is a tutorial example JavaScript that shows you how to truncate and iterate array elements with the "length" property:
<html> <!-- Loop_Array_Elements.html Copyright (c) 2002 HerongYang.com. All Rights Reserved. -> <head><title>Loop Array Elements</title></head> <body> <pre> <script type="text/javascript"> // Creating an empty array var even_numbers = new Array(); // Storing 20 elements in the array for (var i=0; i<20; i++) { even_numbers[i] = i*2; } // Truncating the array length to 10 even_numbers.length = 10; // Iterating all 10 elements document.write("First 10 even numbers: "); for (var i=0; i<even_numbers.length; i++) { document.write(even_numbers[i]+", "); } </script> </pre> </body> </html>
The output of this sample JavaScript is:
First 10 even numbers: 0, 2, 4, 6, 8, 10, 12, 14, 16, 18,
Table of Contents
ECMAScript Language Specification and JavaScript Dialects
Data Types, Variables and Expressions
►Creating, Accessing, and Manipulating Arrays
Accessing Array Elements with Indexes
►Truncating and Iterating Array Elements
Array Object Instance Method Examples
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