javascript self invoking function parameter

The sample javascript self invoking function is defined as follows
(function(parmeter1){
    alert(parameter1);
}("hello world");

Notice the data in the last parentices is the actual caller that will invoke the function, which passes the argument's value as "hello world".
Inside the function definition, the parameter1 is replaced by the string "hello world", and shows the alert.

addSubView and pushViewController difference

For ios project, addSubView and PushViewController can be used to display a new view. However, they are quite different.

addSubView is a instance method of View class, and it adds a view item into itself. If the subview occupies the whole screen, then it has the same effect of display a new view.

pushViewController is a instance method if UINavigationViewController, so it can only be used on UINavigationViewController object, it has a better isolation than previous method, as it does not add the new view as a subview in the parent view.

Array returned from jQuery selector and html element

When using jquery id selector, it will only return a single object. However, similar to other jquery selector, the returned object is wrapped in a jquery object array. Note all jquery selector methods return an array, as it is always possible to match more than one elements for the selector.
If you call a jquey method to retrieve the attribute on the returned array, like val(), it actually returns the attribute of the first element. When the object is selected by id, it is perfectly fine, as there is only one element. However, if the array contains multiple elements, it does not have much sense to just return the first element's value when calling the method on the array. Although, in both cases, setting the value is fine, as it makes sense to set the same value for all elements or a single element.
In order to return a particular jquery element from a multiple element array, call jQuery('selector:eq(index)') method. Remember, the returned value from the method is still wrapped in a jquery array, the only difference is the array will only contain a single jquery object.
In order to return a particular htmlElement, call jQuery('selector').get(index). The returned object is a single html object, (not a array, not a jquery object), and it has all the applicable attribute defined for html element such as value attribute.

Nil and NSNull and NSDictionary

Nil and Null cannot be added into NS collection such as NSDictionary as a value. That is why when checking whether a key exists or not in a dictionary, the following code will work

if ([mydict objectForKey:@"mykey"]) {
    // key exists.
}

However, what about if we really want to add the value for a key that is nil? In this case NSNull is what we want. NSNull can be added in the NSDictionary and also retrieved to represent a nil value.

jquery constructor with context $(selector,this)

Inside the jquery event handler, quite often we need to select a sub element within the passed in event element, and do some operation on it. The passed in event element is accessible from the this object. That is the place you will see a lot of $("selector", this) get called.

$(selector, this) is another jquery constructor, the second parameter takes a context variable. In this case, instead of selecting the elements from the current document, it just selects the matched elements from the context parameter. In the event handler, "this" represents the DOM object that the current event happens on it, to use the jquery method on it, we need first converts it to jquery object with $(this).

Common jquery shortcut

$(...)
=>

jQuery()

All jquery methods are started by calling jQuery(), which can be written as $(...)

$(function(){...});

=> 
$(document).ready(function(){...});

The function will be called when document is ready.

Do not mix this shortcut with javascript self-invoked anonymous function, the ending () makes the js function to be invoked, and thbe leading () indicates this is not normal function.
(function(){
...
})();

$.fn.myFeature = function () { ... } 

=>

jQuery.prototype.myFeature = function () { ... } 

The function to create a jquery plugin by adding method into p

MVC for asp.net web form developer

For asp.net web form deveoper, when starting work with MVC, you may need to know few key points.

1. MVC does not have the rich UI controls available on web form
Reading any MVC books, you will be supprised none of them talking much about ui controls. So how can you put the treeview, or gridview control to your web page? The answer is MVC is an open framework, it is created to to incooperate the new web technology easily, like HTML5, jquery, etc, so it cannot define the ui control's mark up as web form does. So by design, it depends you to select and use any ui markup you get, and for now the answer is jquery ui, or other third party jquery ui extension.

2. MVC does not associate request/response to a backend individual.
Unlike web form, each client request or response is assocated to a backend aspx file, MVC lets you associate a backend method in controller class to each client request and response, this allows to incooperate the partial page render, and other ajax features easily. This is much better than web form, and it is key improment in MVC.

3. MVC dependency: javascript, jquery, CSS, ajax
Unlike what you heard from most MS experts, or MVC books, MVC does not depend on lambada expression, Linq or Entity Framework. In my opinion, you better avoid those topic when first learning MVC, as they have nothing to do with the key points of MVC. The really dependency of MVC are jquery, CSS and ajax. As they are the necessary elements to make a good MVC project.

In addition, I did not see much value in using Entity Framework, or Workflow Framework in your project, it allow you do certain things more easy, but on the other hand, you lose the fine control of the project due to those generated code. It has the same issue as the generated typed Dataset in ADO.NET. I would rather to spend a little more time and know exactly which line of code is doing what, than save some time but having a bunch of files doing things magically without I know the details. There are too many genius in Microsoft, but not enough commonsense.