Home arrow JavaScript arrow Page 3 - Form Validation with JavaScript

Object Lessons - JavaScript

javascriptForm validation can help to reduce the amount of bad data that gets saved to your database. In this article, find out how you can write a simple JavaScript form validator for basic client-side validation, and learn a little bit about JavaScript OOP in the process as well.

TABLE OF CONTENTS:
  1. Form Validation with JavaScript
  2. Check Point
  3. Object Lessons
  4. Rock On
  5. Hammer Time
  6. How Things Work
  7. A Little Space
  8. Expressing Yourself
  9. Under Construction
  10. A Quick Snack
By: Nariman K, (c) Melonfire
Rating: starstarstarstarstar / 464
December 01, 2003

print this article
SEARCH DEV SHED

TOOLS YOU CAN USE

advertisement
Before we get into object construction, a quick primer is in order, for all of you who are new to the weird and wonderful world of objects.

In JavaScript, an "object" is simply a set of program statements which perform a specific task; they lay down the basic rules for an object, specifying what it can and cannot do. A typical object constructor contains both variables and functions, and serves as the template from which to spawn specific instances of that object.

Every object constructed from the template has certain characteristics, or "properties," and certain pre-defined functions, or "methods." These properties and methods of the object correspond directly with the variables and functions within the object definition.

Once an object has been defined, JavaScript allows you to spawn as many instances of the object as you like. Each of these instances is a completely independent object, with its own properties and methods, and can thus be manipulated independently of other objects.

Now, you're probably wondering whether this is a little redundant, since JavaScript also allows you to create your own functions and use them wherever required in your code. And you're correct, to some extent; if you're only planning to spawn a single object, a function will work just as well.

But there are situations where you need to spawn more than one instance of an object - for example, multiple menu trees, multiple image swaps, or multiple ticker tapes. In such a situation, objects are preferred, since each instance comes with its own variables and functions, and thus can be manipulated without affecting other variables within the program.

Objects also help you keep your code modular - you can define an object constructor in a separate file, and include that file only in the pages where you plan to use the object - and simplify code changes, since you only need to edit a single file to add new functionality to all your spawned objects.

 
 
>>> More JavaScript Articles          >>> More By Nariman K, (c) Melonfire
 

blog comments powered by Disqus
escort Bursa Bursa escort Antalya eskort
   

JAVASCRIPT ARTICLES

- Javascript for Beginners: An Introduction
- Introduction to JavaScript
- Adding Elements to a Tree with TreeView jQue...
- Using the Persist Argument in a TreeView jQu...
- Using Unique and Toggle in a TreeView jQuery...
- Using Event Delegation for Mouseover Events ...
- Using the Animate Option in a Treeview jQuer...
- Using HTML Lists with Event Delegation in Ja...
- Opened and Closed Branches on a TreeView jQu...
- Mouseover Events and Event Delegation in Jav...
- Creating a TreeView JQuery Hierarchical Navi...
- Event Delegation in JavaScript
- A Look at the New YUI Carousel Control
- Working with Draggable Elements and Transpar...
- Displaying Pinned Handles with Resizable Con...

Developer Shed Affiliates

 


Dev Shed Tutorial Topics: