<!DOCTYPE html>
<title>drag &amp; drop - dropping folders</title>
<style>
  body > div {
    height: 200px;
    width: 200px;
    background-color: orange;
  }
</style>

<script>
var fails = [], finished = false;
window.onload = function() {
  var orange = document.getElementsByTagName('div')[0];
  orange.ondragover = orange.ondragenter = function(e) {
    e.preventDefault();
    e.dataTransfer.dropEffect = 'copy';
    if( !e.dataTransfer.files ) {
      fails[fails.length] = 'No dataTransfer.files for '+e.type;
    }
    if( !window.FileList ) {
      fails[fails.length] = 'No FileList interface object';
      return;
    }
    if( !( e.dataTransfer.files instanceof FileList ) ) {
      fails[fails.length] = 'dataTransfer.files is not a FileList';
    } else if( e.dataTransfer.files.length ) {
      fails[fails.length] = 'dataTransfer.files.length is '+e.dataTransfer.files.length+' instead of 0 for '+e.type;
    }
  };
  orange.ondrop = function(e) {
    e.preventDefault();
    if( !e.dataTransfer.files ) {
      fails[fails.length] = 'No dataTransfer.files for '+e.type;
    }
    if( !window.FileList ) {
      fails[fails.length] = 'No FileList interface object';
      finish();
      return;
    }
    if( !( e.dataTransfer.files instanceof FileList ) ) {
      fails[fails.length] = 'dataTransfer.files is not a FileList';
    }
    //browsers represent it as a single file (name matching the folder)
    //also allow no files, since that is a valid solution
    if( e.dataTransfer.files.length > 1 ) {
      //dropping the contents of the folder would be crazy, since there could literally be millions of files, or the entire disk contents
      fails[fails.length] = 'dataTransfer.files.length is '+e.dataTransfer.files.length+' instead of 1 for '+e.type;
    }
    if( !e.dataTransfer.files[0] ) {
      finish();
      return;
    }
    /*
    Windows 7 sometimes randomly assigns size to folders, and that is presented to the browser.
    Strangely, packing and unpacking that folder can remove its size.
    Since this is an OS quirk that we have no control over, the test will not check the size.
    if( e.dataTransfer.files[0].size ) {
      fails[fails.length] = 'dataTransfer.files[0].size '+e.dataTransfer.files[0].size+' instead of 0';
    }
    */
    /*
    if( !e.dataTransfer.files[0].lastModified ) {
      fails[fails.length] = 'no dataTransfer.files[0].lastModified';
    }
    */
    if( !window.FileReader ) {
      fails[fails.length] = 'No FileReader constructor';
      finish();
      return;
    }
    var reader = new FileReader();
    reader.onload = function () {
      fails[fails.length] = 'File managed to load even though it was a folder '+e.type;
      finish();
    };
    reader.onerror = function () {
      finish();
    };
    try {
      reader.readAsBinaryString(e.dataTransfer.files[0]);
    } catch(err) {
      fails[fails.length] = 'Threw an error when trying to read the file '+e.type;
      finish();
      return;
    }
    setTimeout(function () {
      fails[fails.length] = 'Onerror failed to fire '+reader.error.code;
      finish();
    },1000);
  };

};
function finish() {
  if( finished ) { return; }
  finished = true;
  document.getElementsByTagName('p')[0].innerHTML = fails.length ? ( 'FAIL: ' + fails.join('<br>') ) : 'PASS';
}
</script>

<div></div>

<p>Drag a folder containing at least 2 files, from your computer's file manager, onto the orange box above. If a no-drop cursor was shown and no text changes when the folder is dropped, pass and ignore further conditions. If a prompt appears, accept it. Fail if the mouse cursor makes it look like it will work but nothing happens.</p>
<p>This test needs to be repeated with:</p>
<ul>
  <li>A regular folder containing at least 2 items</li>
  <li>A disk drive (if your OS exposes them) containing at least 2 items</li>
  <li>The system trash/recycle bin folder (if your OS exposes one) containing at least 2 items</li>
  <li>The &quot;My Computer&quot; folder (if your OS provides it)</li>
  <li>Your &quot;My Documents&quot; folder (if your OS provides it)</li>
  <li>A folder that you do not have permissions to access</li>
</ul>
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