AJAX

AJAX(Asynchronous JavaScript and XML) is a group of methods in web development that are used primarily on client-side in order to create dynamic and interactive web applications. With Ajax, web applications can retrieve data from the server asynchronously in the background without interfering with the display and behavior of the existing page.

Ajax is not a technology, but more a set of technologies that are merged and used together. The main technologies incorporated in Ajax are:

  • HTML, XHTML, CSS, DHTML – used for creating the webpage layout
  • XML and XSLT – for interchanging and manipulating data received
  • XMLHttpRequest – used for asynchronous communications between the web client and server
  • Javascript – dynamically modify the web page without reloading it
  • Commonly PHP, ASP or other server-side script are used.

Using Ajax have it’s advantages:

  • Faster web page loading
  • A more user-friendly web experience
  • Bandwidth friendly – instead of sending the hole page at every request, it sends only a part of it
  • Frameworks – there are many Ajax frameworks available for use for developers

Also, using Ajax may come with disadvantages:

  • web crawlers from the search engines will not be able to index Ajax pages
  • if a browser is set to block Javascript, then it will not be able to properly display the page
  • Ajax pages can not be bookmarked
  • the Ajax code can be seen by the user, which sometime consists with security issues

An example of Ajax use would be the Google Suggestion Box

In the backend, every time a character is typed of the search box, the client will send a request to Google to search its database for every entry that starts with the character typed. Google will search the DB and will send a list to the client. The client will then process the list will dynamically change the suggestions, without reloading the page.

References:

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About Stefan Fodor

inscriptie pe un mormant
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