Social Vitamin » JavaScript

Yahoo! Query Language (YQL)

Michael D. Irizarry — Fri, 10 Jul 2009 15:09:18 +0000

The Yahoo! Query Language is an expressive SQL-like language that lets you query, filter, and join data across Web services. With YQL, apps run faster with fewer lines of code and a smaller network footprint.

Yahoo! and other websites across the Internet make much of their structured data available to developers, primarily through Web services. To access and query these services, developers traditionally endure the pain of locating the right URLs and documentation to access and query each Web service.

With YQL, developers can access and shape data across the Internet through one simple language, eliminating the need to learn how to call different APIs.

How Do I Get Started?

Check out the YQL Console.
Read how to access YQL from your application.
Get your API Keys to sign your requests if you need them.

10 jQuery 1.3 Tips and Tricks for everyday use

Michael D. Irizarry — Mon, 18 May 2009 17:22:18 +0000

Some useful jQuery Tips and Tricks for your everyday use. Removing and Hiding Dom Elements, Browser Detection, Toggling, Handling Select Lists and more.

1. Removing, Showing or Hiding DOM elements

// Remove Element
$("#div").remove();
 
// Hide
$("#div").hide();
$("#div").hide("slow"); 
$("#div").hide("fast");
$("#div").hide(1000);  
$("#div").hide(1000, callback); 
 
// Show
$("#div").show();
$("#div").show("slow"); 
$("#div").show("fast");
$("#div").show(1000);  
$("#div").show(1000, callback);  
 
// Toggle Hide/ Show
$("#div").toggle();
$("#div").toggle("slow");

2. Select All Check Boxes

// Check
$("#selectList").attr('checked', true); 
 
// Uncheck
$("#selectList").attr('checked', false);

3. Creating Images on the Fly

$("").attr({ "src": "images/loadingAnimation.gif" }).appendTo("#div");

4. jQuery noConflict used when using other libraries

var $j = jQuery.noConflict();
$j('#div').hide();

5. Getting Selected Radio Button value

$("input[name='id'][checked]").val();

6. Getting Select List values

// Value
$('#selectList').val(); 
 
// Text value
$('#selectList :selected').text() 
 
// Multiple Selection
var selections = [];
$('#multipleList :selected').each(function(i, selected){
     selections[i] = $(selected).text();
});

7. Check if checkbox is Checked

$('#checkBox').attr('checked'); 
 
$('#checkBoxID').is(':checked'); 
 
$("[:checkbox]:checked").each(
    function() {
    } 
);

8. Browser Detection

if( $.browser.safari ) { // Do something }
 
if ($.browser.msie && $.browser.version > 6 ) { // Do something }
 
if ($.browser.msie && $.browser.version <= 6 ) { // Do something }
 
if ($.browser.mozilla && $.browser.version >= "1.8" )  { // Do something }

9. Highlight a Row onClick

$("tr").click(function() {
    $(this).toggleClass("rowActive");
});

/* CSS highlights clicked row */
.rowActive {  
    border: 1px solid #333333; 
    background-color: #999999; 
}

10. Building the DOM Dynamically

$("").attr({id:"header", "class":"header"}).html("Welcome to my Site!").appendTo(document.body);
$("").attr("src", "images/logo.gif").appendTo("#header");

Paging with LINQ in ASP.NET MVC

Michael D. Irizarry — Sat, 25 Apr 2009 13:19:19 +0000

Here’s a really neat and simple way to add pagination to your LINQ results in ASP.NET MVC. The simple class can be also implemented in non ASP.NET MVC projects.
Note: You can change the source parameter to be List or just add a method overload.

PaginatedList Class

using System;
using System.Linq;
using System.Collections.Generic;
 
namespace MyApp.Helpers
{
    public class PaginatedList<T> : List<T>
    {
 
        public int PageIndex { get; private set; }
        public int PageSize { get; private set; }
        public int TotalCount { get; private set; }
        public int TotalPages { get; private set; }
 
        public PaginatedList(IQueryable<T> source, int pageIndex, int pageSize)
        {
            PageIndex = pageIndex;
            PageSize = pageSize;
            TotalCount = source.Count();
 
            TotalPages = (int) Math.Ceiling(TotalCount / (double)PageSize);
 
            this.AddRange(source.Skip((PageIndex) * PageSize).Take(PageSize));
        }
 
        public bool HasPreviousPage
        {
            get {return (PageIndex > 0);}
        }
 
        public bool HasNextPage {
            get {return (PageIndex+1 < TotalPages);}
        }
 
    }
}

Controller

        public ActionResult Index(int? page)
        {
            int pageSize = 15;
            var content = MyAppRepository.FindContentByDate().ToList();
            var pagedContent = new PaginatedList<Content>(content, page ?? 0, pageSize);
 
            return View("Index", pagedContent);
        }

View

        
        <% if (Model.HasPreviousPage) { %>
        
            <%= Html.RouteLink("Previous", "Index", new { page = (Model.PageIndex - 1) })%>
        
        <% } %>
 
        <% if (Model.HasNextPage) { %>
        
            <%= Html.RouteLink("Next", "Index", new { page = (Model.PageIndex + 1) })%>
        
        <% } %>

Routes in Global.asax

routes.MapRoute(
                "Index",
                "Index/Page/{page}",
                new { controller = "Home", action = "Index", page = 0 }
            );

Random CSS themes give your Social Space a Design Twist

Michael D. Irizarry — Sat, 11 Apr 2009 05:18:31 +0000

Many sites are using this technique to give a fresh interface on every page the user visits, giving the illusion of a fast passed user experience. Sites like MTV, Hulu, MP3.com and many others use different techniques to change the sites layout either by changing the colors, backgrounds or just converting the site to a huge ad campaign.

I came up with a simple PHP script to Random your Themes. It checks for CSS files on a specified folder and randomizes it. You can also set the parameter (theme.php?file=theme.css) if you want to have a static version. Note: Security has been stripped for clarity, setup up the script with your own security.

PHP


 
// Themes Folder
$folder = './';
 
// File Type Default CSS
$fileTypes = array();
$fileTypes['css'] = 'text/css';
 
// File
$file = null;
 
// Sanity Check
if (substr($folder,-1) != '/') {
	$folder = $folder.'/';
}
 
// Request Param
if (isset($_GET['file'])) {
	$meta = pathinfo($_GET['file']);
	if (
	    isset( $fileTypes[ strtolower( $meta['extension'] ) ] ) &&
        file_exists( $folder.$meta['basename'] )
    ) {
		$file = $folder.$meta['basename'];
	}
} else {
	$fileList = array();
 
	if (is_dir($folder)) {
	    if ($handle = opendir($folder)) {
	        while (($file = readdir($handle)) !== false) {
				$file_info = pathinfo($file);
				if ( isset( $fileTypes[ strtolower( $file_info['extension'] ) ] ) ) {
					$fileList[] = $file;
				}
	        }
	        closedir($handle);
	    }
	}
 
	if (count($fileList) > 0) {
		$rnd = rand(0, count($fileList)-1);
		$file = $folder.$fileList[$rnd];
	}
}
 
// Header and Content
if ($file != null) {
	$meta = pathinfo($file);
	$contentType = 'Content-type: '.$fileTypes[ $meta['extension'] ];
	header ($contentType);
	readfile($file);
} 
?>

USE

JS detecting event support in browsers

Michael D. Irizarry — Fri, 03 Apr 2009 04:08:16 +0000

As you may know there is no easy way of detecting which elements supports which events across browsers. Kangax from Perfection Kills has come up with a very clever way of detecting them.

JavaScript

 
  var isEventSupported = (function(){
    var TAGNAMES = {
      'select':'input','change':'input',
      'submit':'form','reset':'form',
      'error':'img','load':'img','abort':'img'
    }
    function isEventSupported(eventName) {
      var el = document.createElement(TAGNAMES[eventName] || 'div');
      eventName = 'on' + eventName;
      var isSupported = (eventName in el);
      if (!isSupported) {
        el.setAttribute(eventName, 'return;');
        isSupported = typeof el[eventName] == 'function';
      }
      el = null;
      return isSupported;
    }
    return isEventSupported;
  })();

Use

isEventSupported(<"Type of Event>")

For a more detailed description visit Kangax blog

Debouncing Javascript Methods

Michael D. Irizarry — Wed, 01 Apr 2009 03:23:58 +0000

What is debouncing anyways? Debouncing is any kind of hardware device or software that ensures that only a single signal will be acted upon for a single opening or closing of a contact. Imagine you have a form with a few elements that a user may access thru the tab key, on each element you have an onfocus event that will trigger an Ajax call to the server to acquire some data. You could just imagine how you could kill the server with all those Ajax calls! So that’s where debouncing comes into play. With debouncing your assuring that the method will be triggered in the element that the user intended to, although is not perfect it does work better than Throttling.

With this little method writen by John Hann from Unscriptable.com you can add debouncing functionality to your JS methods.

Javascript

var debounce = function (func, threshold, execAsap) {
 
    var timeout;
 
    return function debounced () {
        var obj = this, args = arguments;
        function delayed () {
            if (!execAsap)
                func.apply(obj, args);
            timeout = null;
        };
 
        if (timeout)
            clearTimeout(timeout);
        else if (execAsap)
            func.apply(obj, args);
 
        timeout = setTimeout(delayed, threshold || 100);
    };
 
}

Usage

    // using debounce in a constructor or initialization function to debounce
    // focus events for a widget (onFocus is the original handler):
    this.debouncedOnFocus = this.onFocus.debounce(500, false);
    this.inputNode.addEventListener('focus', this.debouncedOnFocus, false);

TaskSpeed – JS Framework Benchmarking

Michael D. Irizarry — Tue, 31 Mar 2009 19:02:21 +0000

TaskSpeed is a benchmarking tool for JS Frameworks. It includes tests for jQuery, Mootools, Prototype and Dojo. Dojo 1.3 has proven to be the fastest JS framework on common DOM operations.

Make Facebook new home look like Twitters using Greasemonkey

Michael D. Irizarry — Mon, 30 Mar 2009 20:38:22 +0000

Facebook Twitter Style is a small CSS injection to hide some parts of the new Facebook home page to make it cleaner and mimic Twitter, also hides the infamous highlights column. You can also update your twitter status from Facebook using Facebook Twitter Updates script for Greasemonkey.

Post Facebook Updates to Twitter using Greasemonkey

Michael D. Irizarry — Wed, 18 Mar 2009 19:55:01 +0000

I just finished a Greasemonkey script that I call “Facebook Twitter Updates” that lets you post Tweets from Facebooks new “Share” feature in 140 characters or less. You will be able to Tweet from Facebook using Facebooks “Share” feature.