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Ajax introduction
Ajax introduction
Ajax introduction
Ajax introduction
Ajax introduction
Ajax introduction
Ajax introduction
Ajax introduction
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Ajax introduction

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ajax introduction

ajax introduction

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Transcript

  • 1. AJAX• Asynchronous JavaScript And XML• AJAX is based on JavaScript and HTTP requests.
  • 2. HISTORY• 1995 – Java Applets• 1996 – MS IE5 IFrame• 1999/2000 – MS IE5 XMLHTTP ActiveX Control• By 2004 – Other browsers - XMLHttpRequest object• 2005 – Google made it popular through google suggest, gmail and other apps• 2006 – W3C released the first draft specification
  • 3. Technologies• HTML and CSS for marking up and styling information.• The DOM accessed with JavaScript.• The XMLHttpRequest (XHR) object is usually used for exchanging data asynchronously between browser and server.• Common data exchange formats include XML, pre- formatted HTML, plain text, and JSON.
  • 4. Advantages• Page reload avoided to display same common content every time.• The use of asynchronous requests allows the clients Web browser UI to be more interactive and to respond quickly to inputs.• Reduce connections to the server.• State can be maintained throughout a web site.
  • 5. Disadvantages• Browsers "back" button issue.• Difficult for a user to bookmark a particular state of the application.• Web crawlers do not execute JavaScript code, making it difficult to index public pages.• Browser that do not support Ajax or JavaScript, or simply have JavaScript disabled.• The Same origin policy prevents some Ajax techniques from being used across domains.• Testing for malicious attacks and debugging difficult.
  • 6. XMLHttpRequest (XHR)• The open method – (type, url, async, user, password)• The setRequestHeader method – Content-Type, User-Agent, etc• The send method – Parameter content to be sent• The onreadystatechange event listener – readyState (1 for open, 2 for send, 3 for loading, 4 for complete)• The HTTP response – responseXML, responseText
  • 7. Browser Object Model
  • 8. Ajax Libraries• JQuery• ExtJs• Dojo• Prototype• GWT

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