The syntax rules of XML are very simple and logical. The rules are easy to learn, and easy to use.
XML documents must contain one root element that is the parent of all other elements:
<root> <child> <subchild>.....</subchild> </child> </root>
In this example <note> is the root element:
<?xml version="1.0" encoding="UTF-8"?> <note> <to>Tove</to> <from>Jani</from> <heading>Reminder</heading> <body>Don't forget me this weekend!</body> </note>
XML documents form a tree structure that starts at “the root” and branches to “the leaves”.
The image above represents books in this XML:
<?xml version="1.0" encoding="UTF-8"?> <bookstore> <book category="cooking"> <title lang="en">Everyday Italian</title> <author>Giada De Laurentiis</author> <year>2005</year> <price>30.00</price> </book> <book category="children"> <title lang="en">Harry Potter</title> <author>J K. Rowling</author> <year>2005</year> <price>29.99</price> </book> <book category="web"> <title lang="en">Learning XML</title> <author>Erik T. Ray</author> <year>2003</year> <price>39.95</price> </book> </bookstore>
XML documents are formed as element trees.
An XML tree starts at a root element and branches from the root to child elements.
All elements can have sub elements (child elements):
<root> <child> <subchild>.....</subchild> </child> </root>
The terms parent, child, and sibling are used to describe the relationships between elements.
Parents have children. Children have parents. Siblings are children on the same level (brothers and sisters).
All elements can have text content (Harry Potter) and attributes (category=”cooking”).
XML uses a much self-describing syntax.
A prolog defines the XML version and the character encoding:
<?xml version="1.0" encoding="UTF-8"?>
The next line is the root element of the document:
<bookstore>
The next line starts a <book> element:
<book category="cooking">
The <book> elements have 4 child elements: <title>, <author>, <year>, <price>.
<title lang="en">Everyday Italian</title> <author>Giada De Laurentiis</author> <year>2005</year> <price>30.00</price>
The next line ends the book element:
</book>
XML is used in many aspects of web development.
XML is often used to separate data from presentation.
XML does not carry any information about how to be displayed.
The same XML data can be used in many different presentation scenarios.
Because of this, with XML, there is a full separation between data and presentation. Continue reading How Can XML be Used?
XML is a software- and hardware-independent tool for storing and transporting data.
XML stands for eXtensible Markup Language.
XML was designed to store and transport data.
XML was designed to be both human- and machine-readable.
What if you wish to use other frameworks on your pages, while still using jQuery?
As you already know; jQuery uses the $ sign as a shortcut for jQuery.
There are many other popular JavaScript frameworks like: Angular, Backbone, Ember, Knockout, and more.
What if other JavaScript frameworks also use the $ sign as a shortcut?
If two different frameworks are using the same shortcut, one of them might stop working.
The jQuery team have already thought about this, and implemented the noConflict() method.
The jQuery get() and post() methods are used to request data from the server with an HTTP GET or POST request.
Two commonly used methods for a request-response between a client and server are: GET and POST.
GET is basically used for just getting (retrieving) some data from the server. Note: The GET method may return cached data.
POST can also be used to get some data from the server. However, the POST method NEVER caches data, and is often used to send data along with the request.
To learn more about GET and POST, and the differences between the two methods, please read our HTTP Methods GET vs POST article. Continue reading jQuery – AJAX get() and post() Methods
The jQuery load() method is a simple, but powerful AJAX method.
The load() method loads data from a server and puts the returned data into the selected element.
Syntax:
$(selector).load(URL,data,callback);
The required URL parameter specifies the URL you wish to load.
The optional data parameter specifies a set of querystring key/value pairs to send along with the request. Continue reading jQuery – AJAX load() Method
AJAX is the art of exchanging data with a server, and updating parts of a web page – without reloading the whole page.
AJAX = Asynchronous JavaScript and XML.
In short; AJAX is about loading data in the background and display it on the webpage, without reloading the whole page.
Examples of applications using AJAX: Gmail, Google Maps, Youtube, and Facebook tabs.
The most basic filtering methods are first(), last() and eq(), which allow you to select a specific element based on its position in a group of elements.
Other filtering methods, like filter() and not() allow you to select elements that match, or do not match, a certain criteria.