JQuery sortable draggable bug.

JQuery sortable Update event calls twice when you bind it to class, not to id and when you drag item to other connectable block.

Jquery

$(".MyClass1, .MyClass2").sortable({
    connectWith: ".connectedSortable",
    update: function (event, ui) {
                alert("twice!");
            }})

Very simple solution is to change event "update" to "stop":

Jquery

$(".MyClass1, .MyClass2").sortable({

    connectWith: ".connectedSortable",

    stop: function (event, ui) {

                alert("once!");

            }})

Entity Framework. "New transaction is not allowed because there are other threads running in the session."

Task: Resolve error.
Solution: Use new context to update item in iteration.

Explanation:
This exception occurs in the following code:

C#

MyContext db=new MyContext();
var ListOfEntities=from p in db.Entity select p;
foreach(var item in ListOfEntities)
{
    item.Text="Changed!";
    db.SaveChanges();
}

In the following example it will be OK:

C#

MyContext db=new MyContext();

var ListOfEntities=from p in db.Entity select p;

foreach(var item in ListOfEntities)

{

    MyContext anotherDB =new MyContext();

    var MyItem=(from p in anotherDB where p.ID=item.ID select p).FirstOrDefault();

    MyItem.Text="Changed!";

    anotherDB.SaveChanges();

}

ASP.NET MVC 3 bug (Html helpers)

If your model has ID parameter then Html helper will replace it with ID from QueryString.
It will take from here ==> "/MyControler/someaction/ID"
not from here ==> "model=>model.ID"

Solution: Write your html inputs yourself if you have ID parameter in Model.

JQuery clone elements

TASK:
Clone DOM elements.

SOLUTION:
Use .clone() and .appendTo().

EXPLANATION:

In the following example we copy DOM element ".from_to_copy" to ".where_to_copy" without typed data and without javascript's bindings.

JQuery

$(".from_to_copy").clone().appendTo(".where_to_copy");

In this example we copy DOM element with data typed and javascript's bindigs.

JQuery

$(".from_to_copy").clone(true).appendTo(".where_to_copy");

Just change default ".clone()" to ".clone(true)".

JQuery detection of browser

TASK: 
Fix something or do special instructions according to browser type.
SOLUTION: 
Use the flags of $.browser:

• $.browser.webkit
• $.browser.safari (deprecated) 
• $.browser.opera
• $.browser.msie
• $.browser.mozilla

Also, we can detect version of browser using $.browser.version

Jquery.browser and $.browser are synonymous.

EXAMPLE: 

JQuery

if ($.browser.mozilla)
{
alert("The browser is mozilla");
}

JQuery

if ($.browser.msie)
{
alert("The browser is Internet Explorer, version:" + $.browser.version);
}

JQuery select element at index n

TASK:
Select the element at index n within the matched set.


SOLUTION:
$(".example:eq("+index+")").css("color", "red");

EXAMPLE:
Select element at index 1 and set css property "color" to "red":

JQuery

var index=1;
$(".example:eq("+index+")").css("color", "red");

HTML

<div class="example">div index 0</div>
<div class="example">div index 1</div>
<div class="example">div index 2</div>

JQuery index of element

TASK:
Recognize index of element in group on which we clicked.
SOLUTION: 
$("#parent child").index(this);
EXAMPLE:

JQuery

$(document).ready(function() {

    $("#example div").click(function() {
        var index = $("#example div").index(this);
        $("#example_index").html("Index " + index + " was clicked");
    });

});

HTML

<div id="example">
    <div>div index 0</div>
    <div>div index 1</div>
    <div>div index 2</div>
    <div>div index 3</div>
    <div>div index 4</div>
</div>
<div id="example_index">Click one of the above divs</div>