Download binary without triggering onbeforeunload

I want to kick off a file download for a user when he clicks a link, but I have an onbeforeunload handler that I don't want to get invoked when the download begins. To downloads, I currently have an <a> with the 开发者_高级运维href set to the file location but clicking it results in onbeforeunload being invoked in Chrome (not in FF, though).

I know I can set a private flag and check that in the onbeforeunload handler, but is there some way to kick off the download using ajax? I still want the user to see the usual dialogs when they download the file (Open/Save etc).

Ideas?

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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.

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

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

From this answer.

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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?

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I know this answer is really late, but there's a simple solution. Create an iframe dynamically, and set the "src" of it to your download url via JavaScript. This'll kick off the download without triggering the unload event (I think).

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The download attribute answer worked well for me, but before I noticed it, I tried this, which also works. Just in case it's useful in some other cases that aren't download links.

var linksThatDisableWarning = $('a'); // all links
linksThatDisableWarning.on('mousedown', () =>
    window.isclicking = true);
linksThatDisableWarning.on('mouseup', () =>
    setTimeout(() => window.isclicking = false, 200))
window.addEventListener('beforeunload', (event) => {
  if (window.isclicking) return;
  event.preventDefault();
  event.returnValue = '';
});