Selection highlighting

highlight.js

        function getSelectedText(){
            if(window.getSelection){
                return window.getSelection().toString();
            }
            else if(document.getSelection){
                return document.getSelection();
            }
            else if(document.selection){
                return document.selection.createRange().text;
            }
        }
         
        var $ = jQuery;
        var startingP = null;

        $(document).ready (function () {
            $("div.entry p").mousedown(function () {
                startingP = $(this);
            }).mouseup(function () {
                if (startingP === null)
                    return;
                var start = startingP;
                startingP = null;
                var end = $(this);
                var text = getSelectedText ();
                if (text === "")
                    return;
                var fullText = start.text();
                if (start.get(0) === end.get(0)) {
                    var index = start.text().indexOf(text);
                    var TEXT_NODE = 3;
                    var ELEMENT_NODE = 1;
                    var root = start.get(0);
                    var textIndex = 0;
                    var ended = false;
                    var nodes = [];
                    var pushNode = function (node, startIndex, endIndex) {
                        if (!startIndex) 
                            startIndex = 0;
                        if (!endIndex)
                            endIndex = node.textContent.length;
                        
                        nodes.push ({node: node, startIndex: startIndex, endIndex: endIndex});
                    };
                    var analize = function(node) {
                        if (node.nodeType == TEXT_NODE) {
                            var startIndex = 0;
                            var endIndex = 0;
                            if (textIndex + node.textContent.length <= index) { //If we are not on the start of the tag continue
                                textIndex += node.textContent.length;
                                return;
                            } else if (textIndex > index) { //Text is in the middle of the selection
                                if (textIndex + node.textContent.length < index + text.length) { //If the selection continues after the element
                                    pushNode (node);
                                    textIndex += node.textContent.length;
                                } else { //If the selection ends inside this element
                                    pushNode(node, 0, index + text.length - textIndex);
                                    ended = true;
                                    return;
                                }
                            } else if (textIndex + node.textContent.length > index) { //If the selection starts inside this element
                                if (textIndex + node.textContent.length < index + text.length) { //If the sleection continues after the element
                                    pushNode(node, index - textIndex);
                                    textIndex += node.textContent.length;
                                } else {
                                    pushNode(node, index - textIndex, index + text.length - textIndex);
                                    ended = true;
                                    return;
                                }
                            }
                        }
                        var childs = node.childNodes;
                        for (var i = 0; i < childs.length; i++) {
                            if (ended)
                                return;
                            analize(childs[i]);
                        }
                    };
                    var childs = root.childNodes;
                    for (var i = 0; i < childs.length; i++) {
                        if (ended)
                            break;
                        analize(childs[i]);
                    }

                    var serializeNode = function (node, data) {
                        var nthChild = 0;
                        var pivot = node;
                        while ((pivot = pivot.previousSibling) != null) nthChild++;
                        data = nthChild + data;
                        node = node.parentNode;
                        if (node.nodeName != "P") {
                            data = "-" + data;
                            return serializeNode(node, data);
                        } else {
                            pivot = node;
                            nthChild = 0;
                            while ((pivot = pivot.previousSibling) != null) nthChild++;
                            return nthChild + "-" + data;
                        }
                    };
                    var data = "";
                    for (var i = 0; i < nodes.length; i++) {
			            var node = nodes[i];
			           data += serializeNode(node.node, "") + "|" + node.startIndex + "," + node.endIndex + ";";
			        }
			        data = "highlight:" + data.substring(0, data.length - 1);
                    window.location.hash = data;
                }
            });
            var hash = window.location.hash;
            var nodes = [];
            var firstHighlight = null;

            if (hash.substring(0, "#highlight:".length) == "#highlight:") {
                hash = hash.replace("#highlight:", "");
                var nodesData = hash.split(";");
                for (var i = 0; i < nodesData.length; i++) {
                    var nodeInfo = nodesData[i].split ("|");
                    var nodeLocation = nodeInfo [0];
                    var selectionData = nodeInfo [1].split (",");
                    var startIndex = selectionData [0];
                    var endIndex = selectionData [1];
                   var baseNode = $("div.entry").get(0);
                    var subNodes = nodeLocation.split ("-");
                    for (var j = 0; j < subNodes.length; j++) 
                        baseNode = baseNode.childNodes [subNodes [j]];
                    nodes.push ( {node: baseNode, start: startIndex, end: endIndex } );
                }
                for (var i = 0; i < nodes.length; i++) {
                    var node = nodes [i];
                    var text = node.node.data;
                    var preText = text.substring (0, node.start);
                    var spanText = text.substring (node.start, node.end);
                    var postText = text.substring (node.end);
                    var parentNode = node.node.parentNode;
                    if (preText != "") 
                        parentNode.insertBefore (document.createTextNode (preText), node.node);
                    var span = $("<span class='highlight'></span>").text (spanText);
                    span.insertBefore (node.node);
                    if (firstHighlight == null)
                        firstHighlight = span.get (0);
                    if (postText != "")
                        parentNode.insertBefore (document.createTextNode (postText), node.node);
                    $(node.node).remove ();
                }

                var x = 0;
                var y = 0;
              
                while (firstHighlight != null) {
                    x += firstHighlight.offsetLeft;
                    y += firstHighlight.offsetTop;
                    firstHighlight = firstHighlight.offsetParent;
                } 
                window.scrollTo (x, y);
                
            }
        });