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I posted this on the ESRI forum a while back but got no response.

PROBLEM: GetImageUrl is called twice resulting in two trips to the server if caching is off.

QUESTION: How can this be prevented (other than turn browser caching on)?


  1. Go to any sample with a dynamic layer (e.g. https://developers.arcgis.com/en/javascript/jssamples/layout_mapcontainersplitinthree.html)
  2. Run a tool like fiddler2 to monitor IP traffic
  3. Resize the browser
  4. Notice that two identical requests are sent:

A single call to map._resize results in getImageUrl being called twice (once for the resize and once for the change of extent).

I am looking for a way to eliminate the redundant call with a minimal amount of coding.

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This isn't an answer, hence the reason I'm posting a comment, but why can't you use browser caching? –  Derek Swingley Feb 28 '12 at 16:41
I agree that in practice it's not going to be an issue but on our dev box when profiling it looks bad and it's an issue ESRI may wish to address if a simple workaround is found. It may not be a simple fix without access to the ESRI source. –  ca0v Feb 28 '12 at 16:54

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