Download binary without triggering onbeforeunload

The best way to do this is indeed by constructing an iframe and triggering the download from there.

I have tested this in Chrome, IE6+ and Firefox and this approach seems to work in all of them.

Example code:

function DownloadFile(filePath) {    var downloadIframe = $('<iframe />',         {            id    :    'downloadIframe'                }).appendTo('body');    downloadIframe.attr('src', filePath);}

This will only work properly for a one off download (as we've hard coded an id), if you are triggering multiple downloads, then I suggest you reuse the iframe by storing it in a more widely accessible variable.

Add the download attribute to the a tag, which seems to prevent onbeforeunload from firing:

<a download href="mysite.com"></a>

From this answer.

I would guess using the target attribute on the link could do the trick.

<a href="http://www.example.com/somefile.zip" target="_blank">download</a>

Will not validate (unless using frameset doctype) but it might work.. It will create a new tab or window and then pop a file download (if the http header says it should), but it might leave the new tabs/windows open, or it might close them after saving...

On the other hand I think having a onbeforeunload handler that you sometimes do not want to trigger sounds suspicious, why do you need that anyway?