Aurelia Fetch client with HEAD method -

i have simple requirement of fetch (http) client within aurelia: make http request url using method 'head' in order determine if resource exists (but without downloading it).

the call easy make:

this.http.fetch('http://the.url/something.jpg', { method: 'head', mode: 'no-cors' })     .then(response => { this.urlisvalid = response.status === 200; })     .catch(error => { ... handle error }); 

however, fetch client never appears enter .then() method, gets caught .catch().

1. if url exists, or there other error reported server (404, 405, 500 etc), error object 'blank' response (i.e. has properties expect, values empty).
2. if url invalid error object contains message 'unable fetch'.

i'm sure i'm missing something, isn't obvious what. can offer solution?

this using aurelia 1.0.0 beta.

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update: requested headers (as captured chrome) 1 of requests comes through blank..

url exists:

request url:https://xxx/the/url.pdf request method:head status code:200 ok remote address:xx.xx.xx.xx:443 accept-ranges:bytes connection:keep-alive content-length:278188 content-type:application/pdf date:mon, 08 feb 2016 00:12:21 gmt etag:"955492e4afe7b2199e15cfafd747df27" last-modified:sun, 13 dec 2015 01:20:37 gmt server:amazons3 via:1.1 xxxxxxx.cloudfront.net (cloudfront) x-amz-cf-id:g7dk2pgwdnrkaznkkovjm0luyb78dvdizlb26x-mgbzi8bc9oua75q== x-cache:miss cloudfront 

403:

request url:https://xxx/invalid/file.pdf request method:head status code:403 forbidden remote address:xx.xx.xx.xx:443 connection:keep-alive content-type:application/xml date:mon, 08 feb 2016 00:16:12 gmt server:amazons3 via:1.1 xxxxxx.cloudfront.net (cloudfront) x-amz-cf-id:q1id8nggywgebf8prquu5l5a--ekglm7x2glbke-rvv45lxv7ch2vg== x-cache:error cloudfront 

your response not blank, opaque. opaque responses can not read , result requesting mode: "no-cors". need set mode mode: "cors" allow responses accessed then, server should set proper cors headers when answering head request.