Javascript selected text highlighting prob

I have a html page with text content. On selecting any text and pressing the highlight button, I can change the style of the selected text to highlight the same. To implement this feature, i have written the following method.

sel = window.getSelection();
var range = sel.getRangeAt(0);
var span = document.createElement('span');
span.className = "highlight" + color;
range.surroundContents(span);

This is working fine if you choose a text with no html tag, but when the text has any html tag in between, it is giving error

Failed to execute ‘surroundContents’ on ‘Range’: The Range has partially selected a non-Text node.

How to solve this problem. Is it possible to highlight the same separately for each part(divided by html tags)?

Answer

if (window.getSelection) {
                var sel = window.getSelection();
                if (!sel) {
                    return;
                }
                var range = sel.getRangeAt(0);
                var start = range.startContainer;
                var end = range.endContainer;
                var commonAncestor = range.commonAncestorContainer;
                var nodes = [];
                var node;

                for (node = start.parentNode; node; node = node.parentNode){
                   var tempStr=node.nodeValue;
                   if(node.nodeValue!=null &&    tempStr.replace(/^s+|s+$/gm,'')!='')
                     nodes.push(node);
                   if (node == commonAncestor)
                     break;
                }
                nodes.reverse();

                for (node = start; node; node = getNextNode(node)){
                   var tempStr=node.nodeValue;
                   if(node.nodeValue!=null &&  tempStr.replace(/^s+|s+$/gm,'')!='')
                     nodes.push(node);
                   if (node == end)
                    break;
                }

                for(var i=0 ; i<nodes.length ; i++){

                   var sp1 = document.createElement("span");
                   sp1.setAttribute("class", "highlight"+color );
                   var sp1_content = document.createTextNode(nodes[i].nodeValue);
                   sp1.appendChild(sp1_content);
                   var parentNode = nodes[i].parentNode;
                   parentNode.replaceChild(sp1, nodes[i]);
                }
           }