replace text in place

gistfile1.js

var iframe = document.getElementById('bannerContent_ifr')
function replaceQuotes(text){
	return text.replace(/(.)/g,function($1){
		var c=$1.charCodeAt(0), n=$1;
		switch(c){
			case 8220: case 8221:
				n='"';
				break;
			case 8216: case 8217:
				n="'";
				break;
		}
		return n;
	});
}
function onDOMModified(event){
    var ignoreKeyCodes="13 16 17 18 20 27 33 34 35 36 37 38 39 40"
	if (ignoreKeyCodes.indexOf(event.keyCode.toString())!==-1) {
	    return;
	}
	if(event.target.watchAndReplace===true){
		return;
	}
    event.target.watchAndReplace=true;
	iframe.contentWindow.setTimeout(function(){
		try{
			var selection=iframe.contentWindow.document.getSelection();
			var range=selection.getRangeAt(0).cloneRange();
			var nodeWithCursor=

range.endContainer;
			window.nodeWithCursorRange=range;
			var loffset=range.endOffset-(nodeWithCursor.nodeValue.length-range.endOffset);
			var content=replaceQuotes(nodeWithCursor.nodeValue);
		    nodeWithCursor.nodeValue=content;
		    range.selectNode(nodeWithCursor);
		    range.setStartAfter(nodeWithCursor);
			selection.removeAllRanges();
			selection.addRange(range);        
		}catch(e){
			if(console && console.warn)console.warn(e.message);
		}finally{
			console.log("delete our watcher");
    		delete event.target.watchAndReplace;
		}
	},80);
}
iframe.contentWindow.document.body.addEventListener("focus", function( event ) {
	event.stopImmediatePropagation();
	event.stopPropagation();
	event.cancelBubble=true;
    event.target.style.outline = "1px solid pink";
    var doc=iframe.contentWindow.document;
	doc.addEventListener("keyup", onDOMModified, false);
}, false);
iframe.contentWindow.document.body.addEventListener("blur", function( event ) {
	event.stopImmediatePropagation();
	event.stopPropagation();
	event.cancelBubble=true;
    event.target.style.outline = "";
    var doc=iframe.contentWindow.document;
	doc.removeEventListener("keyup", onDOMModified, false);
}, false);