Jquery Get content and attribute

jQuery - Get Content and Attributes
jQuery contains powerful methods for changing and manipulating HTML elements and attributes.
jQuery DOM Manipulation
One very important part of jQuery, is the possibility to manipulate the DOM.
jQuery comes with a bunch of DOM related methods, that makes it easy to access and manipulate elements and attributes.
DOM = Document Object Model The DOM defines a standard for accessing HTML and XML documents: "The W3C Document Object Model (DOM) is a platform and language-neutral interface that allows programs and scripts to dynamically access and update the content, structure, and style of a document."

Get Content - text(), html(), and val()
Three simple, but useful, jQuery methods for DOM manipulation is:
 text() - Sets or returns the text content of selected elements
 html() - Sets or returns the content of selected elements (including HTML markup)
 val() - Sets or returns the value of form fields
The following example demonstrates how to get content with the jQuery text() and html() methods:

Example
$("#btn1").click(function(){
alert("Text: " + $("#test").text());
}); $("#btn2").click(function(){
 alert("HTML: " + $("#test").html());
});

The following example demonstrates how to get the value of an input field with the jQuery val() method:
Example
$("#btn1").click(function(){
 alert("Value: " + $("#test").val());
 });

Get Attributes - attr()
The jQuery attr() method is used to get attribute values.
The following example demonstrates how to get the value of the href attribute in a link:
Example
$("button").click(function(){
alert($("#w3s").attr("href"));
 });

jQuery - Set Content and Attributes
Set Content - text(), html(), and val()
We will use the same three methods from the previous page to set content:
 text() - Sets or returns the text content of selected elements
 html() - Sets or returns the content of selected elements (including HTML markup)
 val() - Sets or returns the value of form fields
The following example demonstrates how to set content with the jQuery text(), html(), and val() methods:
Example
$("#btn1").click(function(){
 $("#test1").text("Hello world!");
});
$("#btn2").click(function(){
$("#test2").html("<b>Hello world!</b>");
 }); $("#btn3").click(function(){
 $("#test3").val("Dolly Duck");
 });

A Callback Function for text(), html(), and val()
All of the three jQuery methods above: text(), html(), and val(), also come with a callback function. The callback function has two parameters: the index of the current element in the list of elements selected and the original (old) value. You then return the string you wish to use as the new value from the function.
The following example demonstrates text() and html() with a callback function:
Example

$("#btn1").click(function(){
 $("#test1").text(function(i,origText){
 return "Old text: " + origText + " New text: Hello world! (index: " + i + ")";
 });
});
$("#btn2").click(function(){
 $("#test2").html(function(i,origText){
 return "Old html: " + origText + " New html: Hello <b>world!</b> (index: " + i + ")";
 });
 });

Set Attributes - attr()
The jQuery attr() method is also used to set/change attribute values.
The following example demonstrates how to change (set) the value of the href attribute in a link:

Example
$("button").click(function(){
$("#w3s").attr("href","http://www.w3schools.com/jquery");
 });
The attr() method also allows you to set multiple attributes at the same time.
The following example demonstrates how to set both the href and title attributes at the same time:

Example
$("button").click(function(){
 $("#w3s").attr({
"href" : "http://www.w3schools.com/jquery",
"title" : "W3Schools jQuery Tutorial" });
});

A Callback Function for attr()
The jQuery method attr(), also come with a callback function. The callback function has two parameters: the index of the current element in the list of elements selected and the original (old) attribute value. You then return the string you wish to use as the new attribute value from the function.
The following example demonstrates attr() with a callback function:
Example
$("button").click(function(){
 $("#w3s").attr("href", function(i,origValue){
 return origValue + "/jquery";
 });
 });