Get Pasted Image from Clipboard Firefox

Question

I'm trying to allow the user to paste an image into a div. The problem is that I need it work in Firefox.

From what I've read, Firefox since version 13 (I think) doesn't allow JavaScript access to the clipboard, and event.clipboard doesn't exist in it. I know it can be done because Gmail and Yahoo alow it even in Firefox.

I just want it to work in anyway posible, be with jQuery, JavaScript, HTML5, it doesn't matter as long as it works in the latest Firefox. (No Flash though).

Answer 1

I used the code from this question for my cross-browser paste implementation.. it works in all browsers I have tested (scroll down for the actual solution/code). It should be noted that event.clipboardData expires immediately after the paste event has completed execution.

I went ahead and quadruple checked that this does work in Firefox version 19 (I don't have 13 available, but it sounds like this question was about degradation of a feature in newer versions).

Below is the answer, quoted from Nico Burns:

Solution

Tested in IE6+, FF 3.5+, recent-ish versions of Opera, Chrome, Safari.

function handlepaste (elem, e) {
  var savedcontent = elem.innerHTML;
  if (e && e.clipboardData && e.clipboardData.getData) {// Webkit - get data from clipboard, put into editdiv, cleanup, then cancel event
    if (/text\/html/.test(e.clipboardData.types)) {
      elem.innerHTML = e.clipboardData.getData('text/html');
    }
    else if (/text\/plain/.test(e.clipboardData.types)) {
      elem.innerHTML = e.clipboardData.getData('text/plain');
    }
    else {
      elem.innerHTML = "";
    }
    waitforpastedata(elem, savedcontent);
    if (e.preventDefault) {
      e.stopPropagation();
      e.preventDefault();
    }
    return false;
  }
  else {// Everything else - empty editdiv and allow browser to paste content into it, then cleanup
    elem.innerHTML = "";
    waitforpastedata(elem, savedcontent);
    return true;
  }
}

function waitforpastedata (elem, savedcontent) {
  if (elem.childNodes && elem.childNodes.length > 0) {
    processpaste(elem, savedcontent);
  }
  else {
    that = {
      e: elem,
      s: savedcontent
    }
    that.callself = function () {
      waitforpastedata(that.e, that.s)
    }
    setTimeout(that.callself,20);
  }
}

function processpaste (elem, savedcontent) {
  pasteddata = elem.innerHTML;
  //^^Alternatively loop through dom (elem.childNodes or elem.getElementsByTagName) here

  elem.innerHTML = savedcontent;

  // Do whatever with gathered data;
  alert(pasteddata);
}

<div id='div' contenteditable='true' onpaste='handlepaste(this, event)'>Paste</div>

Explanation

The onpaste event has the handlepaste function attached to it, and passed two arguments: this (i.e. a reference to the element that the event is attached to) and event which is the event object.

---

The handlepaste function:

The first line simply saves the content of the editable div to a variable so it can be restored again at the end.

The if checks whether the browser is an webkit browser (chrome or safari), and if it is it sets contents of the editable div to the data being pasted. It then cancels the event to prevent webkit pasting anything twice. This is because webkit is awkward, and won't paste anything if you simply clear the div.

If it is not a webkit browser then it simply clears the editable div.

It then calls the waitforpastedata function

---

The waitforpastedata function:

This is necessary because the pasted data doesn't appear straight away, so if you just called processpaste straight away then it wouldn't have any data to process.

What it does is check if the editable div has any content, if it does then calls processpaste, otherwise it sets a timer to call itself and check again in 20 milliseconds.

---

The processpaste function:

This function saved the innerHTML of the editable div (which is now the pasted data) to a variable, restores the innerHTML of the editable div back to its original value, and the alert the pasted data. Obviously in a real usage scenario you would probably want to something other than just alert data, you can do whatever you like with it from here.

You will probably also want to run the pasted data through some kind of data sanitising process. This can be done either while it is still in the editable div, or on the extracted string.

---

In a real sitution you would probably want to save the selection before, and restore it afterwards (Set cursor position on contentEditable <div>). You could then insert the pasted data at the position the cursor was in when the user initiated the paste action.

P.S. The combination of this code, IE <= 8 and jsfiddle doesn't seem to work, but it does work in ie <= 8 in a non-jsfiddle environment.