AJAX Http Requests
AJAX Uses HTTP Requests
In traditional JavaScript coding, if you want to get any information from a database or a file on the server, or send
user information to a server, you will have to make an
HTML form and GET or POST data to the server. The user will have to click
the "Submit" button to send/get the information, wait for the server to respond, then a new page will load with the
results.
Because the server returns a new page each
time the user submits input, traditional web applications can
run slowly and tend to be less user-friendly.
With AJAX, your JavaScript communicates directly with the server, through the
JavaScript XMLHttpRequest object
With an HTTP request, a web page can make a request to, and get a response from a web
server - without reloading the page. The user will stay on the same page, and he
or she will
not notice that scripts request pages, or send data to a
server in the background.
The XMLHttpRequest Object
By using the XMLHttpRequest object, a web developer can update a page with data from the server
after the page has loaded!
AJAX was made popular in 2005 by Google (with Google Suggest).
Google Suggest
is using the XMLHttpRequest object to create a very dynamic web interface:
When you start typing in Google's search box, a JavaScript sends the letters off
to a server and the server returns a list of suggestions.
The XMLHttpRequest object is supported in Internet Explorer 5.0+, Safari 1.2,
Mozilla 1.0 / Firefox, Opera 8+, and Netscape 7.
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