Book Image

PHP jQuery Cookbook

By : Vijay Joshi
Book Image

PHP jQuery Cookbook

By: Vijay Joshi

Overview of this book

As web technology evolves, the gap between desktop applications and web applications continues to vanish. And what better way to bridge that gap, for your own website, than using the best two open source technologies in the market: PHP and jQuery. The power-combo of these two is leading the way in revolutionizing the RIA world. Although they are easy to integrate, finding or figuring out how to do what you want to do is rather arduous.The PHP jQuery Cookbook will be your handy guide with walkthroughs of common integration tasks and problems that will help you master the possibilities available using the PHP and jQuery combo. You will learn quick solutions to necessary tasks to integrate the power of two of the best known and most widely used web technologies of today – PHP on the server side and jQuery on the client side. Glide through the basics and move to advanced topics to create dynamic and interactive web applications with this book in hand.This book covers a wide array of technical aspects of creating an interactive website. Apart from basics of PHP and jQuery, you will go through advanced topics like creating plugins, validating controls, and useful utilities that you will be able to use as stand-alone tools. AJAX, the key technique of browser-server communication is covered in detail. You will also learn to use JSON, which is becoming preferred as a mode of data interchange over XML, both in web applications and web services.The book also covers database interaction, which is an important part of any dynamic web application. You will also gain expertise in debugging JavaScript with the help of useful tools that will save you hours of tedious manual debugging.Most importantly, by using jQuery and PHP together, you will be able to develop applications that are compatible with all major browsers, with no need to write code targeted at specific browsers!

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PHP jQuery Cookbook
Vijay Joshi
Dec, 2010 | 332 pages
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Table of Contents (17 chapters)
PHP jQuery Cookbook
PHP jQuery Cookbook
Credits
Credits
About the Author
About the Author
About the Reviewers
About the Reviewers
www.PacktPub.com
www.PacktPub.com
Preface
Preface
Free Chapter
1
Handling Events with jQuery
Handling Events with jQuery
Introduction
Executing functions when page has loaded
Binding and unbinding elements
Adding events to elements that will be created later
Submitting a form with jQuery
Checking for missing images
Creating the select/unselect all checkboxes functionality
Capturing mouse events
Creating keyboard shortcuts
Displaying user selected text
Dragging elements on a page
2
Combining PHP and jQuery
Combining PHP and jQuery
Introduction
Fetching data from PHP using jQuery
Creating a query string automatically for all form elements
Detecting an AJAX request in PHP
Sending data to PHP
Aborting AJAX requests
Creating an empty page and loading it in parts
Handling errors in AJAX requests
Preventing browser from caching AJAX requests
Loading JavaScript on demand to reduce page load time
3
Working with XML Documents
Working with XML Documents
Introduction
Loading XML from files and strings using SimpleXML
Accessing elements and attributes using SimpleXML
Searching elements using XPath
Reading an XML using DOM extension
Creating an XML using DOM extension
Modifying an XML using DOM extension
Parsing XML with jQuery
4
Working with JSON
Working with JSON
Introduction
Creating JSON in PHP
Reading JSON in PHP
Catching JSON parsing errors
Accessing data from a JSON in jQuery
5
Working with Forms
Working with Forms
Introduction
Adding input fields dynamically in a form
Searching for user-inputted string in a page
Checking for empty fields using jQuery
Validating numbers using jQuery
Validating e-mail and website addresses using regular expressions
Displaying errors as user types: Performing live validation
Strengthening validation: validating again in PHP
Creating a voting system
Allowing HTML inside text areas and limiting HTML tags that can be used
6
Adding Visual Effects to Forms
Adding Visual Effects to Forms
Introduction
Creating a Tic-Tac-Toe game with effects
Informing a user while an AJAX request is in progress
Creating expandable and collapsible boxes (accordion)
Fading an element after updating it
Floating box on demand
Updating items in a shopping cart
7
Creating Cool Navigation Menus
Creating Cool Navigation Menus
Introduction
Creating a basic drop-down menu
Creating a menu that changes background on mouse-over
Creating an accordion style menu
Creating a floating menu
Creating an interface for tabbed navigation
Adding more tabs
Creating a wizard using tabs
8
Data Binding with PHP and jQuery
Data Binding with PHP and jQuery
Introduction
Fetching data from a database and displaying it in a table format
Collecting data from a form and saving to a database
Filling chained combo boxes that depend upon each other
Checking username availability from database
Paginating data for large record sets
Adding auto-suggest functionality to a textbox
Creating a tag cloud
9
Enhancing your Site with PHP and jQuery
Enhancing your Site with PHP and jQuery
Introduction
Sending cross-domain requests using server proxy
Making cross-domain requests with jQuery
Creating an endless scrolling page
Creating a jQuery plugin
Displaying RSS feeds with jQuery and PHP
Firebug
Firebug
Introduction
Inspecting elements
Editing HTML and CSS
Debugging JavaScript
Index
Index

Checking for missing images

If you are displaying some images in the browser and unfortunately some of the images are missing, the browser will either display a blank space or will display a placeholder with a cross symbol. This surely looks ugly and you would definitely want to avoid it. Wouldn't it be good if you had a method with which you could find missing images or those that failed to load?

After going through this recipe you will be able to detect missing images and replace them with an image of your choice.

Getting ready

Get three or four images from your computer. You will need these with this recipe. Also keep the jQuery file handy. Create another image using a program like paint with text "Could not load image" written on it. This will be the default placeholder for images that fail to load.

How to do it...

  1. Create a new file in the chapter1 directory and name it as error.html.

  2. Place a DIV in the page, which will be filled with images. Also, write some CSS to style the DIV and the images.

    <html>
  <head>
    <title>Check missing images</title>
    <style type="text/css">
    div
    {
      border:1px solid black;
      float:left;
    }
    img
    {
      width:180px;
      height:200px;
      margin:10px;
    }
    </style>
    
  </head>
  <body>
    <div id="imageContainer"></div>
  </body>
</html>

  3. Write the jQuery code that creates an array of image names. Intentionally put some random names of images that do not exist. Then fill the DIV by creating image tags from this array. Next, bind the error() event handler to the image elements.

    <script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript">
  $(document).ready(function ()
  {
    var images= ['himalaya.png', 'chaukori.png', 'tree.png', 'noSuchimage.png',  'anotheNonExistentImage.png'];
    var html = '';
    $.each(images,function(key, value)
    {
      html+= '<img src="'+value+'" />';
    });
    $('#imageContainer').html(html);

    $('img').error(function()
    {
      $(this).replaceWith('<img src="missing.png" alt="Could not load image">');
    });
  });
</script>

  4. Run the error.html file in a browser. You will see that the last two images, which do not exist, have been replaced by another image that says Could not load image.

How it works...

First we use jQuery's $.each() method to iterate in the array that holds image names and fills the DIV by creating image tags.

Then there is an error() event handler attached to image tags. This gets executed when the image fails to load or has a broken src attribute. The event handler for the error() method replaces the nonexistent image with another image of our choice. In our case we replace it with an image that we have created and that says Could not load image.

See also

  • Binding and unbinding elements, which explains the basics of adding events.

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