This was cross-posted to the ESRI Javascript API forum yesterday.

I need help in interpreting what I am seeing and wondering why I'm seeing duplicate features.

I'm using this example: http://help.arcgis.com/en/webapi/jav...efinition.html "Feature layer with layer definition applied" on my own server and viewing the results after opening the page in Firefox. I modified the tooltip code so I can see the OBJECTID. Your results may be different from what I describe here. I used the tooltip to find the OBJECTID on screen and then expanded the URLs to find the same OBJECTID. I'm specifically looking at the shaded area next to the I-35 sign on the map.

When I expand the keys under the URLs in the JSON tab on the NET tab I can see where the featurelayer (fields) is being created (the line starts as GET1?). Then there are 3 more lines that when expanded have a key called "features". The first one has 1 feature (0), the second line has 4 features (0,1,2,3) and the third line has 2 features (0,1).

In the second line with 4 features, the 4th feature has an OBJECTID of 5095 and in the third line the 2nd feature has an OBJECTID of 5095. Does that mean that this feature is being downloaded twice? I'm not moving the map around at all.

There are also URLs that when expanded do not show any features. They appear to show the same keys as the ones I described above but the features key cannot be expanded. These have a size of 2.6kb. I'm not sure what is happening here.

In this example the sizes that are being downloaded are not a big deal. In my own data I have some large features and when I run this example against my own internal data and limit the definition expression to one feature I get six URLs returned. I'm assuming the first two are about the creation of the actual feature layer. The next four seem to be pairs of duplicates. The URLs with a size of 865B have a key called features that appears to be empty. The URLs with a size of 4.2KB have a key called features that is listing the feature I defined.

So, I asked myself if in fact it was downloading the feature twice. Am I interpreting these results correctly?

enter image description here

  • Please post your code here, (preferably along with a JS fiddle) along with the image. Don't expect people to go to the ESRI forums to see the image and solve your issue. Commented Mar 22, 2013 at 15:30
  • As a newbie on this site I don't have a high enough reputation to post images or multiple links. Probably not code either. Here is a link to the live sample. bit.ly/11px2co. It is not so much of solving an issue but more of "am I understanding this correctly?"
    – MapGuyMike
    Commented Mar 22, 2013 at 15:40

1 Answer 1


In your image the subsequent requests are "304 Not Modified". This means that the client has requested an item which the server had already provided and that the feature has not changed since it was last modified. The client therefore uses it's own cache. So no you are not downloading the feature twice.

  • @MapGuyMike if this doesn't answer your question comment as to why it doesn't or edit your post. Otherwise mark it as answered Commented Oct 17, 2013 at 7:18

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