<input> accept Attribute in Microsoft Edge
Anyone know how to get accept working in Edge?
<input type="file" accept=".csv">
Works fine in Chrome 44, Firefox 39, IE 11, Opera 31.
<input type="file" accept=".csv,text/csv">
"accept" attributes are definitely not supported in Microsoft Edge at this point. I confirmed your behavior as "no go" in edge, but showing up in IE via the [...] thing in the upper right of Edge.
The Edge status shows it as "Under Consideration" with just 198 votes at https://wpdev.uservoice.com/forums/257854-microsoft-edge-developer/suggestions/13661175-full-spec-support-for-accept-in-input-type-file .
If you're interested in implementation of the HTTP Client Hints (aka "accept") on Edge be sure and vote it up at the URL above.
To answer the question: at the moment, Edge does not support accept on <input type="file" />.
There is are plenty of open issues here.