: JQuery/AJAX on old Computers/Browsers I am working on a plattform that will have a lot of users in the so called "developing countries". So many of them will be using old computers and old

@Caterina187

On the server side, you can detect the browser by looking at the HTTP_USER_AGENT header: support.microsoft.com/en-us/kb/306576 You can then use different versions of javascript files for different browsers like

<script type='text/javascript' src='MainLibraryIE6.js'></script>


Another trick is using browser conditional commands such as

<!--[if IE 6]>
<script type="text/javascript" src="FixIE6Problems.js"></script>
<![endif]-->


Also, JQuery 1.9 supports IE 8. JQuery 2.0 only supports IE 9 and higher.

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@Annie201

Depending on the country, the browser usage is very different. In China, for instance, there is 22%+ IE6. When developing for old browsers, keep in mind that even if they support ajax and other fancy javascript stuff, they probably do it a lot slower than more modern browsers.

We did a comparison for a customer project some time ago. IE6, compared to a Firefox 4 was more than ten times slower in javascript execution speed, so we had to add a lot of tweaks (for instance do not add js click handlers on dom ready event, but on mouse over of each element seperately). It's also a good idea to show loading/waiting indicators to the user during expensive js tasks to prevent further clicking which will again cost performance.

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