CORS lets one ArcGIS JavaScript (REST) request through but not the other

Question

I have a problem with Cross-Origin-Requests invoked by the ArcGIS Javascript API.

I'm able to access my web app without any issues if I use localhost:8080. But a REST call (by the ArcGIS JS API) fails if I use mymachine.local.

The exportImage REST call works properly but the query REST call invoked by featureLayer.selectFeatures fails with a Not allowed by Access-Control-Allow-Origin error.

I've gone through http://blogs.esri.com/esri/arcgis/2011/09/29/cross-origin-resource-sharing-cors-with-the-arcgis-api-for-javascript/ but I don't think there's a problem with the CORS setup as one request goes through and the other one fails.

Answer 1

Images are allowed in cross-domain requests, as are some other types of resource. You can read some of the limitations and reasons behind them here