NetworkError on XMLHttpRequest.send()

JonathanBailey

Only when using the Edge browser, I'm getting a generic NetworkError (code 19) when calling XMLHttpRequest.send() against an ArcGIS Online REST endpoint. I have an array of feature service URLs, and I loop through the array to query each feature service for its layers. Following is a code snippet:

Array<SPAN class="punctuation token">.</SPAN><SPAN class="token function">forEach</SPAN><SPAN class="punctuation token">(</SPAN>featureServiceURLs<SPAN class="punctuation token">,</SPAN> lang<SPAN class="punctuation token">.</SPAN><SPAN class="token function">hitch</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="keyword token">this</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="keyword token">function</SPAN> <SPAN class="punctuation token">(</SPAN>featureServiceURL<SPAN class="punctuation token">)</SPAN> <SPAN class="punctuation token">{</SPAN>
&nbsp;&nbsp;&nbsp; 
&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">var</SPAN> url <SPAN class="operator token">=</SPAN> featureServiceURL <SPAN class="operator token">+</SPAN> <SPAN class="string token">"/layers?f=json&token="</SPAN> <SPAN class="operator token">+</SPAN> token<SPAN class="punctuation token">;</SPAN>
&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">var</SPAN> xmlHTTPRequest <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">new</SPAN> <SPAN class="token class-name">XMLHttpRequest</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
&nbsp;&nbsp;&nbsp; xmlHTTPRequest<SPAN class="punctuation token">.</SPAN><SPAN class="token function">open</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="string token">"GET"</SPAN><SPAN class="punctuation token">,</SPAN> url<SPAN class="punctuation token">,</SPAN> <SPAN class="keyword token">false</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
&nbsp;&nbsp;&nbsp; xmlHTTPRequest<SPAN class="punctuation token">.</SPAN><SPAN class="token function">send</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">var</SPAN> response <SPAN class="operator token">=</SPAN> JSON<SPAN class="punctuation token">.</SPAN><SPAN class="token function">parse</SPAN><SPAN class="punctuation token">(</SPAN>xmlHTTPRequest<SPAN class="punctuation token">.</SPAN>responseText<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>

&nbsp;&nbsp;&nbsp; <SPAN class="comment token">// ... additional code to handle response</SPAN>

<SPAN class="punctuation token">}</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍<SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

If the array contains only one URL, then everything works fine. If it contains more than one URL, a NetworkError occurs after the first call to XMLHttpRequest.send().

This behaviour is not observed in Chrome or Firefox.

ThomasSolow

I've never used synchronous http requests.  It seems possible to me that this is an issue with synchronous http request support in some browsers.  I'd try an async pattern to see if that changes anything.

If you're pulling in the Esri JS API you could also use esriRequest which provides a nice wrapper around xmlHttpRequest and returns a promise.