Prevent drag & drop (it's dropping anywhere)

Question

我正在使用这个AngularJS拖放库 ，文档令人困惑，而且已经过时了，但是效果是，即使没有地方放它，它也总是会掉落。

Answer 1

One thing I didn't understand initially is that event.preventDefault() inside ondragover is the way to allow drop (it's kind of backwards from what you might expect). Hence me searching phrases like "how to prevent drag & drop".

Anyway, the problem was Aha, it's an issue with the library, which seems to have some lines of code to handle some old situation which no longer happens. So technically it's not actually dropping at all, but it is calling the onDropSuccess function no matter what.

This issue onDropSuccess will always trigger in IE and Firefox on Windows summarizes the issue, and the fix I've used is to remove these lines from function determineEffectAllowed (e) :

if (e.dataTransfer && e.dataTransfer.dropEffect === 'none') {
  if (e.dataTransfer.effectAllowed === 'copy' ||
    e.dataTransfer.effectAllowed === 'move') {
    e.dataTransfer.dropEffect = e.dataTransfer.effectAllowed
  } else if (e.dataTransfer.effectAllowed === 'copyMove' || e.dataTransfer.effectAllowed === 'copymove') {
    e.dataTransfer.dropEffect = e.ctrlKey ? 'copy' : 'move'
  }
}

So it'll just look like this:

function determineEffectAllowed (e) {
  if (e.originalEvent) {
    e.dataTransfer = e.originalEvent.dataTransfer
  }
}