Book Image

Ext JS 3.0 Cookbook

Book Image

Ext JS 3.0 Cookbook

Overview of this book

Using Ext JS you can easily build desktop-style interfaces in your web applications. Over 400,000 developers are working smarter with Ext JS and yet most of them fail to exercise all of the features that this powerful JavaScript library has to offer. Get to grips with all of the features that you would expect with this quick and easy-to-follow Ext JS Cookbook. This book provides clear instructions for getting the most out of Ext JS with and offers many exercises to build impressive rich internet applications. This cookbook shows techniques and "patterns" for building particular interface styles and features in Ext JS. Pick what you want and move ahead. It teaches you how to use all of the Ext JS widgets and components smartly, through practical examples and exercises. Native and custom layouts, forms, grids, listviews, treeviews, charts, tab panels, menus, toolbars, and many more components are covered in a multitude of examples.The book also looks at best practices on data storage, application architecture, code organization, presenting recipes for improving themóour cookbook provides expert information for people working with Ext JS.
Table of Contents (15 chapters)
Ext JS 3.0 Cookbook
Credits
About the Author
About the Reviewer
Preface

Extending a class


This recipe explains how to use a class extension to create a custom field. As an example, you will build a custom TextField component that provides visual feedback indicating that it is a required field. The feedback will consist of a small glyph on the upper-left corner of the field's input elements, as seen in the following screenshot:

How to do it...

  1. 1. Define the namespace that you will use:

    Ext.ns('Ext.ux.form');
    
  2. 2. Define the custom field as an extension of ext.form.TextField and override the onRender() method:

    Ext.ux.form.RequiredTextField = Ext.extend(Ext.form.TextField, {
    allowBlank: false,
    onRender: function(ct, position) {
    
  3. 3. Within onRender() Call the onRender() method of the base class:

    Ext.ux.form.RequiredTextField.superclass.onRender.call(this, ct, position);
    
  4. 4. Moving on to the custom behavior, calculate the glyph's location:

    glyphX = this.el.dom.clientLeft + this.el.dom.offsetLeft + 1;
    glyphY = this.el.dom.clientTop + this.el.dom.offsetTop + 1;
    }
    });
    
  5. 5. Create...