JQuery BlockUI Plugin does not unblock on IE6/7

I had a problem while using the JQuery plugin, blockUI, that the page did not unblock on IE6. However, it worked quite well on Google Chrome and FireFox. The problem turned out to be an unclosed HTML center tag. However, it is not necessarily the center tag, it could be any unclosed tag.

Select Server controls using JQuery

Selecting a server control using JQuery with the following syntax

$('#dropDownList1')

does not always gurantuee to return the control. The idea is that ASP.Net server controls create dynamic ids in case of duplicate control name or if the control is contained within a user control that is placed on page. Therefore, using the above statment will not always return the control except in the default case that the control is inserted directly to the page and there are no naming conflicts. So, In order to select the control using JQuery you will have to use the following statement:

$('#<=dropDownList1.ClientID>')

How to Add/Remove items from a dropdownlist using JQuery

< asp: DropDownList ID="ddlMyCombo" runat="server" ></asp: DropDownList > 

In order to clear a dropdownlist items using JQuery:
$('#ddlMyCombo >option').remove();

for more about the JQuery Seletor expressions take a look on my post JQuery Selector Expressions Demystified

What I am doing here is selecting all the option elements that are child of the element with ID “#ddlMyCombo” which is the dropdownlist id and then deleting them. Doing this is gonna clear all elements of the dropdownlist.

So now in order to add items again to the dropdownlist, we will simply append options HTML elements to our test combo
var myCombo= $('#ddlMyCombo');
myCombo.append($('< option > </option>').val(1).html(option1Text));

What I have done here is that I have selected the dropdownlist first just for convenience. It is similar to saying
document.getElementById('ddlMyCombo')
I then start appending HTML option items to my dropdownlist and set the item value and text.

JQuery filter method .filter( )

The JQuery .filter( ) method is used to select a list of objects that match the applied filter. Filters can be applied whether using selector expressions or JQuery functions:

.find (Selector Expression):

Applying the fitler $('tr').find( ' : odd') on the following HTML snippet
<tr> item 1 </tr>
<tr> item 2 </tr>
<tr> item 3 </tr>
<tr> item 4 </tr>
<tr> item 5 </tr>
<tr> item 6 </tr>

will return item 2, item 4, item 6

for more about the JQuery Seletor expressions take a look on my post JQuery Selector Expressions Demystified

.find (Function):

Applies the specified function on each item and return only those that the function evaluates to true upon.

Applying the filter expression $('tr').find(function(index) { return index == 1;}) will return the second item with index 1.