Find size of file behind download link with jQuery

I feel like this is too much to be doing client-side, but I don’t know the details of your application, so presuming you have to do it with jQuery… you can do a HEAD request and look at the Content-Length header. Earlier I recommended the jqHead plugin, but after I tried to use it I found that it was broken.

Here’s a working example that doesn’t depend on any extra plugins: http://host.masto.com/~chris/so/jqhead.html

The meat of it is very simple:

  var request;
  request = $.ajax({
    type: "HEAD",
    url: $("#url").val(),
    success: function () {
      alert("Size is " + request.getResponseHeader("Content-Length"));
    }
  });