Get and Set Attribute’s Value in jQuery

JQuery library functions have more functionality than we can think of. All we want through jQuery can be easily implemented like to get values of any element on the web-page. Whether the value is simple text or whole html of that element.

Earlier article was about to get content of text, html and value field assigned to an element on the web-page. Element on the web-page have many attributes like id, name, title, href etc. and its corresponding value that is specific for that attribute.

JQuery library function have some in-built function that can be used to get those attributes value and developer can set those values by using other provided functions. For example the following code fragment will get href value of an anchor tag with specified selector:

alert($("#anchor").attr("href"));

This alert message can be included wherever we want like in any button’s click event or any function called as per requirement.

Developer can also set particular value for any attribute of any element. Following example will set an anchor tag’s (above code fragment) href attribute’s value:

$("#anchor").attr("href","http://dotprogramming.blogspot.com");

Same as above function we can easily set attribute’s value either one or multiple at once. Following code will assign title and href attribute’s value for the same anchor tag only in one function:

$("#anchor").attr({
    "href" : " http://dotprogramming.blogspot.com",
    "title" : "JQuery Learning Material"
  });

These functions for set an attribute’s value can be used callback functions to be execute further operation after setting the value. In the next article we will show those callback functions with syntax and execute some more operations.

Get Content and Attributes in jQuery

Getting and assigning content of elements in jQuery is very simple because of its in-built functions. JQuery provides many in-built functions that can be used to get content of any element and can set html part for any element.

JQuery library contains many DOM related functions that make it easy to use and understand how it is working. Programmer can easily manipulate content of any element or attributes by using existing functions. In rare chances programmer have to write its own functions with collection of JQuery library functions.

To get content of any element on the web-page, programmer can use following three mostly used functions:

• val(): get or set the value of forms field.
• text(): get or set the text content of selected elements.
• html(): get of set the whole content of selected elements including html markup.

Lookout the following example through which we will use all three types of functions and show the values returns by them.

$("#btn").click(function(){
alert($("#lblText1").val());
        alert($("#lblText2").text());
        alert($("#lblText3").html());
});

All the above alert messages will return respective values for selected label. The below code fragment will assign some values to all three labels:

$("#btn").click(function(){
alert($("#lblText1").val("value"));
        alert($("#lblText2").text("text"));
        alert($("#lblText3").html("html"));
});

In the next article we will get and set attribute's value for an element on the web-page.

Understanding Attributes in Asp.Net MVC

Earlier article was about to handle browser request from the user and then invokes related controller and actions written for that particular URL. What is to be done after these requests can also be specified by the programmer in Asp.Net MVC, as this article will discuss.

Asp.Net MVC provides a way to use some extra features for actions and controller, these features are called Attributes and Filters. We have discusses about Required attribute in creating MVC View Model using required field validations.

The first and most attribute, MVC use by default is [Authorize] which specifies which action is to be executed by authenticated users only or it may be used for whole controller. The syntax for this authorize attribute is:

[Authorize]
Public ActionResult Profile()
{
return View();
}

Now whenever an un-authorized user will try to get access of this profile action, it will redirect the request to login page or the page specified.

Attributes can also take parameters specified in their declaration, they may be positional or named. Positional parameter corresponds to attribute’s public constructor like the one specified below. It will change the name of this action profile to Details, as specified as the parameter.

[ActionName(“Details”)]
Public ActionResult Profile()
{ return View(); }

Named parameter correspond to public property or field of the respective attribute. For example authorize attribute have some named parameters like order, roles and users as written in following code:

[Authorize(Roles="Role1, Role2", Users="User1, User2")]
Public ActionResult Profile()
{ return View(); }

By specifying these named parameters, this profile action will only be accessed by the users having role "Role1" and "Role2". If we talk about the users, this action will only be accessed by only the person having username "User1" and "User2".

Attribute is a class which inherits from the abstract class System.Attribure. 

So we have to inherit from the same System.Attribute class to create our own attribute. Each attribute class (created by us) will must ends with the word "Attribute". E.g.

• AuthorizeAttribute
• RequiredAttribute
• ActionNameAttribute
• CustomizedAttribute
• ValueCheckAttribute

Mapping Browser request
HTML Handlers