This was driving me nuts! I wanted to use a DIV with contenteditable=true, which of course is rich text featured. That is certainly a good thing, but what if you don't want pasted tags to screw up the design in the editable box?
A simple document.execCommand("paste") of course doesn't do it.

I found two different approaches and learned, that there is no clean way to do it.

#1 from Stackoverflow unfortunately didn't work. Chrome didn't know how to handle getData().

editor.addEventListener("paste", function(e) {
    // cancel paste
    e.preventDefault();
    // get text representation of clipboard
    var text = e.clipboardData.getData("text/plain");
    // insert text manually
    document.execCommand("insertHTML", false, text);
});

Another slidely different method did not do the job either (Stackoverflow):

document.querySelector("div[contenteditable]").addEventListener("paste", function(e) {
    e.preventDefault();
    var text = e.clipboardData.getData("text/plain");
    var temp = document.createElement("div");
    temp.innerHTML = text;
    document.execCommand("insertHTML", false, temp.textContent);
});​

#2 also from Stackoverflow uses a hidden textarea to clean up the code. It's a nice idea and I found out, that the textarea must not be display:none or visibility:hidden. However an opacity:0 or height/width:0px leaves it funtional. It filled my hidden textarea with plain text, but pasted HTML in my DIV in the beginning.

$('.editable').live('paste', function()
{
    var $this = $(this);
    //more code here to remember caret position, etc
    $('#clipboard').val('').focus(); //put the focus in the hidden textarea so that, when the paste actually occurs, it's auto-sanitized by the textarea
    setTimeout(function() //then this will be executed immediately after the paste actually occurs
    {
        $this.focus();
        document.execCommand('insertHTML', true, $('#clipboard').val());
    });
});

I used it like this and it worked for me then:

$('#editor').bind('paste', function(e){
	var $this = $(this);
	$('#clipboard').val('').focus();
	setTimeout(function() {
		$this.focus();
		document.execCommand('insertHTML', true, $('#clipboard').val());
	});
});

The problem: It always adds content to the beginning of my DIV, because it switches focus inbetween. I tried some experiments with getSelection() to save the pointer-position with the range, but I finally gave up...

...and started all over again with a great idea I got. It is a lot less browser dependable. The execCommands's are nice, but sometimes very restricted and different in browsers.

Here is my solution:

$('#editor').bind('paste', function(){ // catch the paste-event in the DIV
	// get content before paste
	var before = document.getElementById('editor').innerHTML;
	setTimeout(function(){
		// get content after paste by a 100ms delay
		var after = document.getElementById('editor').innerHTML;
		// find the start and end position where the two differ
		var pos1 = -1;
		var pos2 = -1;
		for (var i=0; i<after.length; i++) {
			if (pos1 == -1 && before.substr(i, 1) != after.substr(i, 1)) pos1 = i;
			if (pos2 == -1 && before.substr(before.length-i-1, 1) != after.substr(after.length-i-1, 1)) pos2 = i;
		}
		// the difference = pasted string with HTML:
		var pasted = after.substr(pos1, after.length-pos2-pos1);
		// strip the tags:
		var replace = pasted.replace(/<[^>]+>/g, '');
		// build clean content:
		var replaced = after.substr(0, pos1)+replace+after.substr(pos1+pasted.length);
		// replace the HTML mess with the plain content
		document.getElementById('editor').innerHTML = replaced;
	}, 100);
});

It works perfectly! And it automatically places the pointer behind the pasted & cleaned content!

I had to do a small correction for the positioning:

var pasted = after.substr(pos1-1, after.length-pos2-pos1+2);
var replaced = after.substr(0, pos1-1)+replace+after.substr(pos1-1+pasted.length);

After taking one more surrounding character, it didn't fail to replace tags after a new line.

function replaceTags() {
  // content of $('editor').bind() from above
}

setInterval(function() {
  // check for tags every 0.1 seconds
  if (document.getElementById('editor').innerHTML.match(/<[^>]+>/)) replaceTags();
}, 100);

$('#editor').bind('paste', replaceTags);

  if(pos1 > 0) pos1 -= 1;
  if(pos2 > 0) pos2 -= 1;

$('[contenteditable]').on('paste', function (e) {
                            e.preventDefault();
                            var cd =  e.originalEvent.clipboardData;
                            $("[contenteditable]").empty().text(cd.getData("text/plain"));
                        });