How to get week number for a date in jQuery

This is a useful function, who tell you week in the year for a custom date.

function(d) {
    
 var day = d.getDay();
 if(day == 0) day = 7;
 d.setDate(d.getDate() + (4 - day));
 var year = d.getFullYear();
 var ZBDoCY = Math.floor((d.getTime() - new Date(year, 0, 1, -6)) / 86400000);
 return 1 + Math.floor(ZBDoCY / 7);
}

How to build a jQuery slideshow

A jQuery slideshow I can say it's the most used small application that you can integrate in a website.
There are many on the internet but the best practice is to create one of your own, by own custom rules.
I will show here a basic slideshow with slide effect:

 Here is a preview , we have numbers for each slide , left/right arrows and a click for details.

In this example images will have a custom width = 940px.


The jQuery code is :

var currentId = 1;
var currentScroll = 0;

$(document).ready(function() {
 // Load the slideshow
 imageRotator();
});

function imageRotator() {

 initialize();
 updateArrows(); 
 bindArrows();
 bindNumbers();

}

function initialize() {
 $('div#rotator ul').empty();
 currentId = 1;
 currentScroll = 0;

 documentWidth = $(window).width();
 $("#rotator #content").width(documentWidth-5);

 nrOfImages = $("div#rotator #content ul li").length;
 buildNumbers(nrOfImages);
 

 $("#rotator #content ul li a").each(function(i){
  $(this).css("left",820 + 940*i)
 
 });
}
function buildNumbers(nrOfImages) {
 $('#navbar').empty();
 var html = "";
 if (nrOfImages === 1) {
  html = "";
  $('#navbar').append(html);
 }
 else {
  for (var i = 1 ; i <= nrOfImages ; i++) {
   html += '



' + i + '
';
  }
  $('#navbar').append(html);
 }
}
function bindArrows() {
 $('#leftArrow').click(function() {
  currentId--;
  currentScroll -= 940;
  changeSlide();
  updateArrows();
 });
 $('#rightArrow').click(function() {
  currentId++;
  currentScroll += 940;
  changeSlide();
  updateArrows();
 });
}
function bindNumbers(){
 $('#navbar div').live('click',function() {
  var select = parseInt($(this).text());

   currentScroll = 940 * (select - 1);
   changeSlide();
   currentId = select;

  updateArrows();
 });
}
function changeSlide() {
 var current = $("#rotator #content");
 current.animate ( {
  scrollLeft : currentScroll
 },1200)

}


function updateArrows() {
 changeSlide();
 total_pictures = $('div#rotator #content1 ul li').length;

 if (currentId === total_pictures) {
  $('#rightArrow').hide();
 } else {
  $('#rightArrow').show();
 }

 if (currentId === 1) {
  $('#leftArrow').hide();
 } else {
  $('#leftArrow').show();
 }

};

The html code is :

<div id = "content">
<ul>

ul>
div>
<div id="navbar">div>

 <div id="leftArrow">div>

<div id="rightArrow">div>
    div>

And inside ul you will have images

Now you need to add css to display things as you want :)

Why jQuery change() don't work in IE

In latest jQuery version change() event don't work in IE , on radio buttons for example , or checkboxes.This happens cause DOM is updated dynamically inIE using AJAX.So the general advice is :

Use click() function instead!
or
Try to bind change() event using new jQuery live :

$("#checkbox").live("change",function() {
    alert("checkbox triggered");
}

Where checkbox is the id of your <.input type = "checkbox" id = "checkbox">

How to get numbers of days in a month

This post shows how to get the number of days in a month using jQuery by passing the month and year to a function.
The function is :

function getDaysInMonth(month, year) {

    return new Date(year, month, 0).getDate();
}

Example :
We want number of days from February 2009

alert(getDaysInMonth(2, 2009));

Output:

28

Why this works?

In fact here : alert(getDaysInMonth(2, 2009)); we ask for day 0 of March, cause months start from 0.But day 0 of March is last day of February, so with this trick we can get days from a custom month and year;