Debugging Multiple Page Loads

Common reasons why a page from the user might be loaded more than once.

Pedantic warning

Per the HTTP specification, GET requests should be "safe" and "idempotent" -- meaning GET requests shouldn't have any side effects and receiving more than of the same request should be the same as if you received only one.

Reasons why a page might be loaded more than once:

• User may have reloaded the page.
• User may have clicked the link multiple times.
• Dynamically-generated <img src> is malformed, such as <img src=""> -- Firefox loads the current page, Safari does not.
• YSlow plug-in for Firefox will reload the page to measure performance.
• NoScript plug-in for Firefox will reload the page if the "Allow Scripts" option is changed.
• Presenting a HTTP Authentication challenge will result in multiple hits to the page.
• Some web accelerators use pre-fetching to pre-load all the links on the page.
• Google AdSense will crawl the page to determine the ads to show to the user.

Author: Bil Corry
Created: 15 May 2009
Last Modified: 1 Mar 2011