diff --git a/www/common/diffDOM.js b/www/common/diffDOM.js
new file mode 100644
index 000000000..18ac7be12
--- /dev/null
+++ b/www/common/diffDOM.js
@@ -0,0 +1,1349 @@
+(function() {
+    "use strict";
+
+    var diffcount;
+
+    var Diff = function (options) {
+        var diff = this;
+        Object.keys(options).forEach(function(option) {
+            diff[option] = options[option];
+        });
+    };
+
+    Diff.prototype = {
+        toString: function() {
+            return JSON.stringify(this);
+        }
+
+        // TODO: compress diff output by replacing these keys with numbers or alike:
+        /*        'addAttribute' = 0,
+                'modifyAttribute' = 1,
+                'removeAttribute' = 2,
+                'modifyTextElement' = 3,
+                'relocateGroup' = 4,
+                'removeElement' = 5,
+                'addElement' = 6,
+                'removeTextElement' = 7,
+                'addTextElement' = 8,
+                'replaceElement' = 9,
+                'modifyValue' = 10,
+                'modifyChecked' = 11,
+                'modifySelected' = 12,
+                'modifyComment' = 13,
+                'action' = 14,
+                'route' = 15,
+                'oldValue' = 16,
+                'newValue' = 17,
+                'element' = 18,
+                'group' = 19,
+                'from' = 20,
+                'to' = 21,
+                'name' = 22,
+                'value' = 23,
+                'data' = 24,
+                'attributes' = 25,
+                'nodeName' = 26,
+                'childNodes' = 27,
+                'checked' = 28,
+                'selected' = 29;*/
+    };
+
+    var SubsetMapping = function SubsetMapping(a, b) {
+        this.old = a;
+        this.new = b;
+    };
+
+    SubsetMapping.prototype = {
+        contains: function contains(subset) {
+            if (subset.length < this.length) {
+                return subset.new >= this.new && subset.new < this.new + this.length;
+            }
+            return false;
+        },
+        toString: function toString() {
+            return this.length + " element subset, first mapping: old " + this.old + " → new " + this.new;
+        }
+    };
+
+    var elementDescriptors = function(el) {
+        var output = [];
+        if (el.nodeName !== '#text' && el.nodeName !== '#comment') {
+            output.push(el.nodeName);
+            if (el.attributes) {
+                if (el.attributes.class) {
+                    output.push(el.nodeName + '.' + el.attributes.class.replace(/ /g, '.'));
+                }
+                if (el.attributes.id) {
+                    output.push(el.nodeName + '#' + el.attributes.id);
+                }
+            }
+
+        }
+        return output;
+    };
+
+    var findUniqueDescriptors = function(li) {
+        var uniqueDescriptors = {},
+            duplicateDescriptors = {};
+
+        li.forEach(function(node) {
+            elementDescriptors(node).forEach(function(descriptor) {
+                var inUnique = descriptor in uniqueDescriptors,
+                    inDupes = descriptor in duplicateDescriptors;
+                if (!inUnique && !inDupes) {
+                    uniqueDescriptors[descriptor] = true;
+                } else if (inUnique) {
+                    delete uniqueDescriptors[descriptor];
+                    duplicateDescriptors[descriptor] = true;
+                }
+            });
+
+        });
+
+        return uniqueDescriptors;
+    };
+
+    var uniqueInBoth = function(l1, l2) {
+        var l1Unique = findUniqueDescriptors(l1),
+            l2Unique = findUniqueDescriptors(l2),
+            inBoth = {};
+
+        Object.keys(l1Unique).forEach(function(key) {
+            if (l2Unique[key]) {
+                inBoth[key] = true;
+            }
+        });
+
+        return inBoth;
+    };
+
+    var removeDone = function(tree) {
+        delete tree.outerDone;
+        delete tree.innerDone;
+        delete tree.valueDone;
+        if (tree.childNodes) {
+            return tree.childNodes.every(removeDone);
+        } else {
+            return true;
+        }
+    };
+
+    var isEqual = function(e1, e2) {
+
+        var e1Attributes, e2Attributes;
+
+        if (!['nodeName', 'value', 'checked', 'selected', 'data'].every(function(element) {
+                if (e1[element] !== e2[element]) {
+                    return false;
+                }
+                return true;
+            })) {
+            return false;
+        }
+
+        if (Boolean(e1.attributes) !== Boolean(e2.attributes)) {
+            return false;
+        }
+
+        if (Boolean(e1.childNodes) !== Boolean(e2.childNodes)) {
+            return false;
+        }
+
+        if (e1.attributes) {
+            e1Attributes = Object.keys(e1.attributes);
+            e2Attributes = Object.keys(e2.attributes);
+
+            if (e1Attributes.length !== e2Attributes.length) {
+                return false;
+            }
+            if (!e1Attributes.every(function(attribute) {
+                    if (e1.attributes[attribute] !== e2.attributes[attribute]) {
+                        return false;
+                    }
+                })) {
+                return false;
+            }
+        }
+
+        if (e1.childNodes) {
+            if (e1.childNodes.length !== e2.childNodes.length) {
+                return false;
+            }
+            if (!e1.childNodes.every(function(childNode, index) {
+                    return isEqual(childNode, e2.childNodes[index]);
+                })) {
+
+                return false;
+            }
+
+        }
+
+        return true;
+
+    };
+
+
+    var roughlyEqual = function(e1, e2, uniqueDescriptors, sameSiblings, preventRecursion) {
+        var childUniqueDescriptors, nodeList1, nodeList2;
+
+        if (!e1 || !e2) {
+            return false;
+        }
+
+        if (e1.nodeName !== e2.nodeName) {
+            return false;
+        }
+
+        if (e1.nodeName === '#text') {
+            // Note that we initially don't care what the text content of a node is,
+            // the mere fact that it's the same tag and "has text" means it's roughly
+            // equal, and then we can find out the true text difference later.
+            return preventRecursion ? true : e1.data === e2.data;
+        }
+
+
+        if (e1.nodeName in uniqueDescriptors) {
+            return true;
+        }
+
+        if (e1.attributes && e2.attributes) {
+
+            if (e1.attributes.id && e1.attributes.id === e2.attributes.id) {
+                var idDescriptor = e1.nodeName + '#' + e1.attributes.id;
+                if (idDescriptor in uniqueDescriptors) {
+                    return true;
+                }
+            }
+            if (e1.attributes.class && e1.attributes.class === e2.attributes.class) {
+                var classDescriptor = e1.nodeName + '.' + e1.attributes.class.replace(/ /g, '.');
+                if (classDescriptor in uniqueDescriptors) {
+                    return true;
+                }
+            }
+        }
+
+        if (sameSiblings) {
+            return true;
+        }
+
+        nodeList1 = e1.childNodes ? e1.childNodes.slice().reverse() : [];
+        nodeList2 = e2.childNodes ? e2.childNodes.slice().reverse() : [];
+
+        if (nodeList1.length !== nodeList2.length) {
+            return false;
+        }
+
+        if (preventRecursion) {
+            return nodeList1.every(function(element, index) {
+                return element.nodeName === nodeList2[index].nodeName;
+            });
+        } else {
+            // note: we only allow one level of recursion at any depth. If 'preventRecursion'
+            // was not set, we must explicitly force it to true for child iterations.
+            childUniqueDescriptors = uniqueInBoth(nodeList1, nodeList2);
+            return nodeList1.every(function(element, index) {
+                return roughlyEqual(element, nodeList2[index], childUniqueDescriptors, true, true);
+            });
+        }
+    };
+
+
+    var cloneObj = function(obj) {
+        //  TODO: Do we really need to clone here? Is it not enough to just return the original object?
+        return JSON.parse(JSON.stringify(obj));
+        //return obj;
+    };
+
+    /**
+     * based on https://en.wikibooks.org/wiki/Algorithm_implementation/Strings/Longest_common_substring#JavaScript
+     */
+    var findCommonSubsets = function(c1, c2, marked1, marked2) {
+        var lcsSize = 0,
+            index = [],
+            matches = Array.apply(null, new Array(c1.length + 1)).map(function() {
+                return [];
+            }), // set up the matching table
+            uniqueDescriptors = uniqueInBoth(c1, c2),
+            // If all of the elements are the same tag, id and class, then we can
+            // consider them roughly the same even if they have a different number of
+            // children. This will reduce removing and re-adding similar elements.
+            subsetsSame = c1.length === c2.length,
+            origin, ret;
+
+        if (subsetsSame) {
+
+            c1.some(function(element, i) {
+                var c1Desc = elementDescriptors(element),
+                    c2Desc = elementDescriptors(c2[i]);
+                if (c1Desc.length !== c2Desc.length) {
+                    subsetsSame = false;
+                    return true;
+                }
+                c1Desc.some(function(description, i) {
+                    if (description !== c2Desc[i]) {
+                        subsetsSame = false;
+                        return true;
+                    }
+                });
+                if (!subsetsSame) {
+                    return true;
+                }
+
+            });
+        }
+
+        // fill the matches with distance values
+        c1.forEach(function(c1Element, c1Index) {
+            c2.forEach(function(c2Element, c2Index) {
+                if (!marked1[c1Index] && !marked2[c2Index] && roughlyEqual(c1Element, c2Element, uniqueDescriptors, subsetsSame)) {
+                    matches[c1Index + 1][c2Index + 1] = (matches[c1Index][c2Index] ? matches[c1Index][c2Index] + 1 : 1);
+                    if (matches[c1Index + 1][c2Index + 1] >= lcsSize) {
+                        lcsSize = matches[c1Index + 1][c2Index + 1];
+                        index = [c1Index + 1, c2Index + 1];
+                    }
+                } else {
+                    matches[c1Index + 1][c2Index + 1] = 0;
+                }
+            });
+        });
+        if (lcsSize === 0) {
+            return false;
+        }
+        origin = [index[0] - lcsSize, index[1] - lcsSize];
+        ret = new SubsetMapping(origin[0], origin[1]);
+        ret.length = lcsSize;
+
+        return ret;
+    };
+
+    /**
+     * This should really be a predefined function in Array...
+     */
+    var makeArray = function(n, v) {
+        return Array.apply(null, new Array(n)).map(function() {
+            return v;
+        });
+    };
+
+    /**
+     * Generate arrays that indicate which node belongs to which subset,
+     * or whether it's actually an orphan node, existing in only one
+     * of the two trees, rather than somewhere in both.
+     *
+     * So if t1 = <img><canvas><br>, t2 = <canvas><br><img>.
+     * The longest subset is "<canvas><br>" (length 2), so it will group 0.
+     * The second longest is "<img>" (length 1), so it will be group 1.
+     * gaps1 will therefore be [1,0,0] and gaps2 [0,0,1].
+     *
+     * If an element is not part of any group, it will stay being 'true', which
+     * is the initial value. For example:
+     * t1 = <img><p></p><br><canvas>, t2 = <b></b><br><canvas><img>
+     *
+     * The "<p></p>" and "<b></b>" do only show up in one of the two and will
+     * therefore be marked by "true". The remaining parts are parts of the
+     * groups 0 and 1:
+     * gaps1 = [1, true, 0, 0], gaps2 = [true, 0, 0, 1]
+     *
+     */
+    var getGapInformation = function(t1, t2, stable) {
+
+        var gaps1 = t1.childNodes ? makeArray(t1.childNodes.length, true) : [],
+            gaps2 = t2.childNodes ? makeArray(t2.childNodes.length, true) : [],
+            group = 0;
+
+        // give elements from the same subset the same group number
+        stable.forEach(function(subset) {
+            var i, endOld = subset.old + subset.length,
+                endNew = subset.new + subset.length;
+            for (i = subset.old; i < endOld; i += 1) {
+                gaps1[i] = group;
+            }
+            for (i = subset.new; i < endNew; i += 1) {
+                gaps2[i] = group;
+            }
+            group += 1;
+        });
+
+        return {
+            gaps1: gaps1,
+            gaps2: gaps2
+        };
+    };
+
+    /**
+     * Find all matching subsets, based on immediate child differences only.
+     */
+    var markSubTrees = function(oldTree, newTree) {
+        // note: the child lists are views, and so update as we update old/newTree
+        var oldChildren = oldTree.childNodes ? oldTree.childNodes : [],
+            newChildren = newTree.childNodes ? newTree.childNodes : [],
+            marked1 = makeArray(oldChildren.length, false),
+            marked2 = makeArray(newChildren.length, false),
+            subsets = [],
+            subset = true,
+            returnIndex = function() {
+                return arguments[1];
+            },
+            markBoth = function(i) {
+                marked1[subset.old + i] = true;
+                marked2[subset.new + i] = true;
+            };
+
+        while (subset) {
+            subset = findCommonSubsets(oldChildren, newChildren, marked1, marked2);
+            if (subset) {
+                subsets.push(subset);
+
+                Array.apply(null, new Array(subset.length)).map(returnIndex).forEach(markBoth);
+
+            }
+        }
+        return subsets;
+    };
+
+
+    function swap(obj, p1, p2) {
+        (function(_) {
+            obj[p1] = obj[p2];
+            obj[p2] = _;
+        }(obj[p1]));
+    }
+
+
+    var DiffTracker = function() {
+        this.list = [];
+    };
+
+    DiffTracker.prototype = {
+        list: false,
+        add: function(diffs) {
+            var list = this.list;
+            diffs.forEach(function(diff) {
+                list.push(diff);
+            });
+        },
+        forEach: function(fn) {
+            this.list.forEach(fn);
+        }
+    };
+
+    var diffDOM = function(options) {
+
+        var defaults = {
+                debug: false,
+                diffcap: 10, // Limit for how many diffs are accepting when debugging. Inactive when debug is false.
+                maxDepth: false, // False or a numeral. If set to a numeral, limits the level of depth that the the diff mechanism looks for differences. If false, goes through the entire tree.
+                valueDiffing: true, // Whether to take into consideration the values of forms that differ from auto assigned values (when a user fills out a form).
+                // syntax: textDiff: function (node, currentValue, expectedValue, newValue)
+                textDiff: function() {
+                    arguments[0].data = arguments[3];
+                    return;
+                },
+                // empty functions were benchmarked as running faster than both
+                // `f && f()` and `if (f) { f(); }`
+                preVirtualDiffApply: function () {},
+                postVirtualDiffApply: function () {},
+                preDiffApply: function () {},
+                postDiffApply: function () {}
+            },
+            i;
+
+        if (typeof options === "undefined") {
+            options = {};
+        }
+
+        for (i in defaults) {
+            if (typeof options[i] === "undefined") {
+                this[i] = defaults[i];
+            } else {
+                this[i] = options[i];
+            }
+        }
+
+    };
+    diffDOM.prototype = {
+
+        // ===== Create a diff =====
+
+        diff: function(t1Node, t2Node) {
+
+            var t1 = this.nodeToObj(t1Node),
+                t2 = this.nodeToObj(t2Node);
+
+            diffcount = 0;
+
+            if (this.debug) {
+                this.t1Orig = this.nodeToObj(t1Node);
+                this.t2Orig = this.nodeToObj(t2Node);
+            }
+
+            this.tracker = new DiffTracker();
+            return this.findDiffs(t1, t2);
+        },
+        findDiffs: function(t1, t2) {
+            var diffs;
+            do {
+                if (this.debug) {
+                    diffcount += 1;
+                    if (diffcount > this.diffcap) {
+                        window.diffError = [this.t1Orig, this.t2Orig];
+                        throw new Error("surpassed diffcap:" + JSON.stringify(this.t1Orig) + " -> " + JSON.stringify(this.t2Orig));
+                    }
+                }
+                diffs = this.findNextDiff(t1, t2, []);
+                if (diffs.length === 0) {
+                    // Last check if the elements really are the same now.
+                    // If not, remove all info about being done and start over.
+                    // Somtimes a node can be marked as done, but the creation of subsequent diffs means that it has to be changed anyway.
+                    if (!isEqual(t1, t2)) {
+                        removeDone(t1);
+                        diffs = this.findNextDiff(t1, t2, []);
+                    }
+                }
+
+                if (diffs.length > 0) {
+                    this.tracker.add(diffs);
+                    this.applyVirtual(t1, diffs);
+                }
+            } while (diffs.length > 0);
+            return this.tracker.list;
+        },
+        findNextDiff: function(t1, t2, route) {
+            var diffs;
+
+            if (this.maxDepth && route.length > this.maxDepth) {
+                return [];
+            }
+            // outer differences?
+            if (!t1.outerDone) {
+                diffs = this.findOuterDiff(t1, t2, route);
+                if (diffs.length > 0) {
+                    t1.outerDone = true;
+                    return diffs;
+                } else {
+                    t1.outerDone = true;
+                }
+            }
+            // inner differences?
+            if (!t1.innerDone) {
+                diffs = this.findInnerDiff(t1, t2, route);
+                if (diffs.length > 0) {
+                    return diffs;
+                } else {
+                    t1.innerDone = true;
+                }
+            }
+
+            if (this.valueDiffing && !t1.valueDone) {
+                // value differences?
+                diffs = this.findValueDiff(t1, t2, route);
+
+                if (diffs.length > 0) {
+                    t1.valueDone = true;
+                    return diffs;
+                } else {
+                    t1.valueDone = true;
+                }
+            }
+
+            // no differences
+            return [];
+        },
+        findOuterDiff: function(t1, t2, route) {
+
+            var diffs = [],
+                attr1, attr2;
+
+            if (t1.nodeName !== t2.nodeName) {
+                return [new Diff({
+                    action: 'replaceElement',
+                    oldValue: cloneObj(t1),
+                    newValue: cloneObj(t2),
+                    route: route
+                })];
+            }
+
+            if (t1.data !== t2.data) {
+                // Comment or text node.
+                if (t1.nodeName === '#text') {
+                    return [new Diff({
+                        action: 'modifyComment',
+                        route: route,
+                        oldValue: t1.data,
+                        newValue: t2.data
+                    })];
+                } else {
+                    return [new Diff({
+                        action: 'modifyTextElement',
+                        route: route,
+                        oldValue: t1.data,
+                        newValue: t2.data
+                    })];
+                }
+
+            }
+
+
+            attr1 = t1.attributes ? Object.keys(t1.attributes).sort() : [];
+            attr2 = t2.attributes ? Object.keys(t2.attributes).sort() : [];
+
+            attr1.forEach(function(attr) {
+                var pos = attr2.indexOf(attr);
+                if (pos === -1) {
+                    diffs.push(new Diff({
+                        action: 'removeAttribute',
+                        route: route,
+                        name: attr,
+                        value: t1.attributes[attr]
+                    }));
+                } else {
+                    attr2.splice(pos, 1);
+                    if (t1.attributes[attr] !== t2.attributes[attr]) {
+                        diffs.push(new Diff({
+                            action: 'modifyAttribute',
+                            route: route,
+                            name: attr,
+                            oldValue: t1.attributes[attr],
+                            newValue: t2.attributes[attr]
+                        }));
+                    }
+                }
+
+            });
+
+
+            attr2.forEach(function(attr) {
+                diffs.push(new Diff({
+                    action: 'addAttribute',
+                    route: route,
+                    name: attr,
+                    value: t2.attributes[attr]
+                }));
+
+            });
+
+            return diffs;
+        },
+        nodeToObj: function(node) {
+            var objNode = {}, dobj = this;
+            objNode.nodeName = node.nodeName;
+            if (objNode.nodeName === '#text' || objNode.nodeName === '#comment') {
+                objNode.data = node.data;
+            } else {
+                if (node.attributes && node.attributes.length > 0) {
+                    objNode.attributes = {};
+                    Array.prototype.slice.call(node.attributes).forEach(
+                        function(attribute) {
+                            objNode.attributes[attribute.name] = attribute.value;
+                        }
+                    );
+                }
+                if (node.childNodes && node.childNodes.length > 0) {
+                    objNode.childNodes = [];
+                    Array.prototype.slice.call(node.childNodes).forEach(
+                        function(childNode) {
+                            objNode.childNodes.push(dobj.nodeToObj(childNode));
+                        }
+                    );
+                }
+                if (this.valueDiffing) {
+                    if (node.value) {
+                        objNode.value = node.value;
+                    }
+                    if (node.checked) {
+                        objNode.checked = node.checked;
+                    }
+                    if (node.selected) {
+                        objNode.selected = node.selected;
+                    }
+                }
+            }
+
+            return objNode;
+        },
+        objToNode: function(objNode, insideSvg) {
+            var node, dobj = this;
+            if (objNode.nodeName === '#text') {
+                node = document.createTextNode(objNode.data);
+
+            } else if (objNode.nodeName === '#comment') {
+                node = document.createComment(objNode.data);
+            } else {
+                if (objNode.nodeName === 'svg' || insideSvg) {
+                    node = document.createElementNS('http://www.w3.org/2000/svg', objNode.nodeName);
+                    insideSvg = true;
+                } else {
+                    node = document.createElement(objNode.nodeName);
+                }
+                if (objNode.attributes) {
+                    Object.keys(objNode.attributes).forEach(function(attribute) {
+                        node.setAttribute(attribute, objNode.attributes[attribute]);
+                    });
+                }
+                if (objNode.childNodes) {
+                    objNode.childNodes.forEach(function(childNode) {
+                        node.appendChild(dobj.objToNode(childNode, insideSvg));
+                    });
+                }
+                if (this.valueDiffing) {
+                    if (objNode.value) {
+                        node.value = objNode.value;
+                    }
+                    if (objNode.checked) {
+                        node.checked = objNode.checked;
+                    }
+                    if (objNode.selected) {
+                        node.selected = objNode.selected;
+                    }
+                }
+            }
+            return node;
+        },
+        findInnerDiff: function(t1, t2, route) {
+
+            var subtrees = (t1.childNodes && t2.childNodes) ? markSubTrees(t1, t2) : [],
+                t1ChildNodes = t1.childNodes ? t1.childNodes : [],
+                t2ChildNodes = t2.childNodes ? t2.childNodes : [],
+                childNodesLengthDifference, diffs = [],
+                index = 0,
+                last, e1, e2, i;
+
+            if (subtrees.length > 1) {
+                /* Two or more groups have been identified among the childnodes of t1
+                 * and t2.
+                 */
+                return this.attemptGroupRelocation(t1, t2, subtrees, route);
+            }
+
+            /* 0 or 1 groups of similar child nodes have been found
+             * for t1 and t2. 1 If there is 1, it could be a sign that the
+             * contents are the same. When the number of groups is below 2,
+             * t1 and t2 are made to have the same length and each of the
+             * pairs of child nodes are diffed.
+             */
+
+
+            last = Math.max(t1ChildNodes.length, t2ChildNodes.length);
+            if (t1ChildNodes.length !== t2ChildNodes.length) {
+                childNodesLengthDifference = true;
+            }
+
+            for (i = 0; i < last; i += 1) {
+                e1 = t1ChildNodes[i];
+                e2 = t2ChildNodes[i];
+
+                if (childNodesLengthDifference) {
+                    /* t1 and t2 have different amounts of childNodes. Add
+                     * and remove as necessary to obtain the same length */
+                    if (e1 && !e2) {
+                        if (e1.nodeName === '#text') {
+                            diffs.push(new Diff({
+                                action: 'removeTextElement',
+                                route: route.concat(index),
+                                value: e1.data
+                            }));
+                            index -= 1;
+                        } else {
+                            diffs.push(new Diff({
+                                action: 'removeElement',
+                                route: route.concat(index),
+                                element: cloneObj(e1)
+                            }));
+                            index -= 1;
+                        }
+
+                    } else if (e2 && !e1) {
+                        if (e2.nodeName === '#text') {
+                            diffs.push(new Diff({
+                                action: 'addTextElement',
+                                route: route.concat(index),
+                                value: e2.data
+                            }));
+                        } else {
+                            diffs.push(new Diff({
+                                action: 'addElement',
+                                route: route.concat(index),
+                                element: cloneObj(e2)
+                            }));
+                        }
+                    }
+                }
+                /* We are now guaranteed that childNodes e1 and e2 exist,
+                 * and that they can be diffed.
+                 */
+                /* Diffs in child nodes should not affect the parent node,
+                 * so we let these diffs be submitted together with other
+                 * diffs.
+                 */
+
+                if (e1 && e2) {
+                    diffs = diffs.concat(this.findNextDiff(e1, e2, route.concat(index)));
+                }
+
+                index += 1;
+
+            }
+            t1.innerDone = true;
+            return diffs;
+
+        },
+
+        attemptGroupRelocation: function(t1, t2, subtrees, route) {
+            /* Either t1.childNodes and t2.childNodes have the same length, or
+             * there are at least two groups of similar elements can be found.
+             * attempts are made at equalizing t1 with t2. First all initial
+             * elements with no group affiliation (gaps=true) are removed (if
+             * only in t1) or added (if only in t2). Then the creation of a group
+             * relocation diff is attempted.
+             */
+
+            var gapInformation = getGapInformation(t1, t2, subtrees),
+                gaps1 = gapInformation.gaps1,
+                gaps2 = gapInformation.gaps2,
+                shortest = Math.min(gaps1.length, gaps2.length),
+                destinationDifferent, toGroup,
+                group, node, similarNode, testI, diffs = [],
+                index1, index2, j;
+
+
+            for (index2 = 0, index1 = 0; index2 < shortest; index1 += 1, index2 += 1) {
+                if (gaps1[index2] === true) {
+                    node = t1.childNodes[index1];
+                    if (node.nodeName === '#text') {
+                        if (t2.childNodes[index2].nodeName === '#text' && node.data !== t2.childNodes[index2].data) {
+                            testI = index1;
+                            while (t1.childNodes.length > testI + 1 && t1.childNodes[testI + 1].nodeName === '#text') {
+                                testI += 1;
+                                if (t2.childNodes[index2].data === t1.childNodes[testI].data) {
+                                    similarNode = true;
+                                    break;
+                                }
+                            }
+                            if (!similarNode) {
+                                diffs.push(new Diff({
+                                    action: 'modifyTextElement',
+                                    route: route.concat(index2),
+                                    oldValue: node.data,
+                                    newValue: t2.childNodes[index2].data
+                                }));
+                            }
+                        }
+                        diffs.push(new Diff({
+                            action: 'removeTextElement',
+                            route: route.concat(index2),
+                            value: node.data
+                        }));
+                        gaps1.splice(index2, 1);
+                        shortest = Math.min(gaps1.length, gaps2.length);
+                        index2 -= 1;
+                    } else {
+                        diffs.push(new Diff({
+                            action: 'removeElement',
+                            route: route.concat(index2),
+                            element: cloneObj(node)
+                        }));
+                        gaps1.splice(index2, 1);
+                        shortest = Math.min(gaps1.length, gaps2.length);
+                        index2 -= 1;
+                    }
+
+                } else if (gaps2[index2] === true) {
+                    node = t2.childNodes[index2];
+                    if (node.nodeName === '#text') {
+                        diffs.push(new Diff({
+                            action: 'addTextElement',
+                            route: route.concat(index2),
+                            value: node.data
+                        }));
+                        gaps1.splice(index2, 0, true);
+                        shortest = Math.min(gaps1.length, gaps2.length);
+                        index1 -= 1;
+                    } else {
+                        diffs.push(new Diff({
+                            action: 'addElement',
+                            route: route.concat(index2),
+                            element: cloneObj(node)
+                        }));
+                        gaps1.splice(index2, 0, true);
+                        shortest = Math.min(gaps1.length, gaps2.length);
+                        index1 -= 1;
+                    }
+
+                } else if (gaps1[index2] !== gaps2[index2]) {
+                    if (diffs.length > 0) {
+                        return diffs;
+                    }
+                    // group relocation
+                    group = subtrees[gaps1[index2]];
+                    toGroup = Math.min(group.new, (t1.childNodes.length - group.length));
+                    if (toGroup !== group.old) {
+                        // Check whether destination nodes are different than originating ones.
+                        destinationDifferent = false;
+                        for (j = 0; j < group.length; j += 1) {
+                            if (!roughlyEqual(t1.childNodes[toGroup + j], t1.childNodes[group.old + j], [], false, true)) {
+                                destinationDifferent = true;
+                            }
+                        }
+                        if (destinationDifferent) {
+                            return [new Diff({
+                                action: 'relocateGroup',
+                                groupLength: group.length,
+                                from: group.old,
+                                to: toGroup,
+                                route: route
+                            })];
+                        }
+                    }
+                }
+            }
+            return diffs;
+        },
+
+        findValueDiff: function(t1, t2, route) {
+            // Differences of value. Only useful if the value/selection/checked value
+            // differs from what is represented in the DOM. For example in the case
+            // of filled out forms, etc.
+            var diffs = [];
+
+            if (t1.selected !== t2.selected) {
+                diffs.push(new Diff({
+                    action: 'modifySelected',
+                    oldValue: t1.selected,
+                    newValue: t2.selected,
+                    route: route
+                }));
+            }
+
+            if ((t1.value || t2.value) && t1.value !== t2.value && t1.nodeName !== 'OPTION') {
+                diffs.push(new Diff({
+                    action: 'modifyValue',
+                    oldValue: t1.value,
+                    newValue: t2.value,
+                    route: route
+                }));
+            }
+            if (t1.checked !== t2.checked) {
+                diffs.push(new Diff({
+                    action: 'modifyChecked',
+                    oldValue: t1.checked,
+                    newValue: t2.checked,
+                    route: route
+                }));
+            }
+
+            return diffs;
+        },
+
+        // ===== Apply a virtual diff =====
+
+        applyVirtual: function(tree, diffs) {
+            var dobj = this;
+            if (diffs.length === 0) {
+                return true;
+            }
+            diffs.forEach(function(diff) {
+                //                              console.log(JSON.stringify(diff));
+                //                              console.log(JSON.stringify(tree));
+                //                              console.log(this.objToNode(tree).outerHTML);
+                dobj.applyVirtualDiff(tree, diff);
+                //                                console.log(JSON.stringify(tree));
+                //                                console.log(this.objToNode(tree).outerHTML);
+            });
+            return true;
+        },
+        getFromVirtualRoute: function(tree, route) {
+            var node = tree,
+                parentNode, nodeIndex;
+
+            route = route.slice();
+            while (route.length > 0) {
+                if (!node.childNodes) {
+                    return false;
+                }
+                nodeIndex = route.splice(0, 1)[0];
+                parentNode = node;
+                node = node.childNodes[nodeIndex];
+            }
+            return {
+                node: node,
+                parentNode: parentNode,
+                nodeIndex: nodeIndex
+            };
+        },
+        applyVirtualDiff: function(tree, diff) {
+            var routeInfo = this.getFromVirtualRoute(tree, diff.route),
+                node = routeInfo.node,
+                parentNode = routeInfo.parentNode,
+                nodeIndex = routeInfo.nodeIndex,
+                newNode, route, c;
+
+            // pre-diff hook
+            var info = {
+                diff: diff,
+                node: node
+            };
+
+            if (this.preVirtualDiffApply(info)) { return true; }
+
+            switch (diff.action) {
+                case 'addAttribute':
+                    if (!node.attributes) {
+                        node.attributes = {};
+                    }
+
+                    node.attributes[diff.name] = diff.value;
+
+                    if (diff.name === 'checked') {
+                        node.checked = true;
+                    } else if (diff.name === 'selected') {
+                        node.selected = true;
+                    } else if (node.nodeName === 'INPUT' && diff.name === 'value') {
+                        node.value = diff.value;
+                    }
+
+                    break;
+                case 'modifyAttribute':
+                    node.attributes[diff.name] = diff.newValue;
+                    if (node.nodeName === 'INPUT' && diff.name === 'value') {
+                        node.value = diff.value;
+                    }
+                    break;
+                case 'removeAttribute':
+
+                    delete node.attributes[diff.name];
+
+                    if (Object.keys(node.attributes).length === 0) {
+                        delete node.attributes;
+                    }
+
+                    if (diff.name === 'checked') {
+                        delete node.checked;
+                    } else if (diff.name === 'selected') {
+                        delete node.selected;
+                    } else if (node.nodeName === 'INPUT' && diff.name === 'value') {
+                        delete node.value;
+                    }
+
+                    break;
+                case 'modifyTextElement':
+                    node.data = diff.newValue;
+
+                    if (parentNode.nodeName === 'TEXTAREA') {
+                        parentNode.value = diff.newValue;
+                    }
+                    break;
+                case 'modifyValue':
+                    node.value = diff.newValue;
+                    break;
+                case 'modifyComment':
+                    node.data = diff.newValue;
+                    break;
+                case 'modifyChecked':
+                    node.checked = diff.newValue;
+                    break;
+                case 'modifySelected':
+                    node.selected = diff.newValue;
+                    break;
+                case 'replaceElement':
+                    newNode = cloneObj(diff.newValue);
+                    newNode.outerDone = true;
+                    newNode.innerDone = true;
+                    newNode.valueDone = true;
+                    parentNode.childNodes[nodeIndex] = newNode;
+                    break;
+                case 'relocateGroup':
+                    node.childNodes.splice(diff.from, diff.groupLength).reverse()
+                        .forEach(function(movedNode) {
+                            node.childNodes.splice(diff.to, 0, movedNode);
+                        });
+                    break;
+                case 'removeElement':
+                    parentNode.childNodes.splice(nodeIndex, 1);
+                    break;
+                case 'addElement':
+                    route = diff.route.slice();
+                    c = route.splice(route.length - 1, 1)[0];
+                    node = this.getFromVirtualRoute(tree, route).node;
+                    newNode = cloneObj(diff.element);
+                    newNode.outerDone = true;
+                    newNode.innerDone = true;
+                    newNode.valueDone = true;
+
+                    if (!node.childNodes) {
+                        node.childNodes = [];
+                    }
+
+                    if (c >= node.childNodes.length) {
+                        node.childNodes.push(newNode);
+                    } else {
+                        node.childNodes.splice(c, 0, newNode);
+                    }
+                    break;
+                case 'removeTextElement':
+                    parentNode.childNodes.splice(nodeIndex, 1);
+                    if (parentNode.nodeName === 'TEXTAREA') {
+                        delete parentNode.value;
+                    }
+                    break;
+                case 'addTextElement':
+                    route = diff.route.slice();
+                    c = route.splice(route.length - 1, 1)[0];
+                    newNode = {};
+                    newNode.nodeName = '#text';
+                    newNode.data = diff.value;
+                    node = this.getFromVirtualRoute(tree, route).node;
+                    if (!node.childNodes) {
+                        node.childNodes = [];
+                    }
+
+                    if (c >= node.childNodes.length) {
+                        node.childNodes.push(newNode);
+                    } else {
+                        node.childNodes.splice(c, 0, newNode);
+                    }
+                    if (node.nodeName === 'TEXTAREA') {
+                        node.value = diff.newValue;
+                    }
+                    break;
+                default:
+                    console.log('unknown action');
+            }
+
+            // capture newNode for the callback
+            info.newNode = newNode;
+            this.postVirtualDiffApply(info);
+
+            return;
+        },
+
+
+
+
+        // ===== Apply a diff =====
+
+        apply: function(tree, diffs) {
+            var dobj = this;
+
+            if (diffs.length === 0) {
+                return true;
+            }
+            diffs.forEach(function(diff) {
+                if (!dobj.applyDiff(tree, diff)) {
+                    return false;
+                }
+            });
+            return true;
+        },
+        getFromRoute: function(tree, route) {
+            route = route.slice();
+            var c, node = tree;
+            while (route.length > 0) {
+                if (!node.childNodes) {
+                    return false;
+                }
+                c = route.splice(0, 1)[0];
+                node = node.childNodes[c];
+            }
+            return node;
+        },
+        applyDiff: function(tree, diff) {
+            var node = this.getFromRoute(tree, diff.route),
+                newNode, reference, route, c;
+
+            // pre-diff hook
+            var info = {
+                diff: diff,
+                node: node
+            };
+
+            if (this.preDiffApply(info)) { return true; }
+
+            switch (diff.action) {
+                case 'addAttribute':
+                    if (!node || !node.setAttribute) {
+                        return false;
+                    }
+                    node.setAttribute(diff.name, diff.value);
+                    break;
+                case 'modifyAttribute':
+                    if (!node || !node.setAttribute) {
+                        return false;
+                    }
+                    node.setAttribute(diff.name, diff.newValue);
+                    break;
+                case 'removeAttribute':
+                    if (!node || !node.removeAttribute) {
+                        return false;
+                    }
+                    node.removeAttribute(diff.name);
+                    break;
+                case 'modifyTextElement':
+                    if (!node || node.nodeType !== 3) {
+                        return false;
+                    }
+                    this.textDiff(node, node.data, diff.oldValue, diff.newValue);
+                    break;
+                case 'modifyValue':
+                    if (!node || typeof node.value === 'undefined') {
+                        return false;
+                    }
+                    node.value = diff.newValue;
+                    break;
+                case 'modifyComment':
+                    if (!node || typeof node.data === 'undefined') {
+                        return false;
+                    }
+                    node.data = diff.newValue;
+                    break;
+                case 'modifyChecked':
+                    if (!node || typeof node.checked === 'undefined') {
+                        return false;
+                    }
+                    node.checked = diff.newValue;
+                    break;
+                case 'modifySelected':
+                    if (!node || typeof node.selected === 'undefined') {
+                        return false;
+                    }
+                    node.selected = diff.newValue;
+                    break;
+                case 'replaceElement':
+                    node.parentNode.replaceChild(this.objToNode(diff.newValue, node.namespaceURI === 'http://www.w3.org/2000/svg'), node);
+                    break;
+                case 'relocateGroup':
+                    Array.apply(null, new Array(diff.groupLength)).map(function() {
+                        return node.removeChild(node.childNodes[diff.from]);
+                    }).forEach(function(childNode, index) {
+                        if (index === 0) {
+                            reference = node.childNodes[diff.to];
+                        }
+                        node.insertBefore(childNode, reference);
+                    });
+                    break;
+                case 'removeElement':
+                    node.parentNode.removeChild(node);
+                    break;
+                case 'addElement':
+                    route = diff.route.slice();
+                    c = route.splice(route.length - 1, 1)[0];
+                    node = this.getFromRoute(tree, route);
+                    node.insertBefore(this.objToNode(diff.element, node.namespaceURI === 'http://www.w3.org/2000/svg'), node.childNodes[c]);
+                    break;
+                case 'removeTextElement':
+                    if (!node || node.nodeType !== 3) {
+                        return false;
+                    }
+                    node.parentNode.removeChild(node);
+                    break;
+                case 'addTextElement':
+                    route = diff.route.slice();
+                    c = route.splice(route.length - 1, 1)[0];
+                    newNode = document.createTextNode(diff.value);
+                    node = this.getFromRoute(tree, route);
+                    if (!node || !node.childNodes) {
+                        return false;
+                    }
+                    node.insertBefore(newNode, node.childNodes[c]);
+                    break;
+                default:
+                    console.log('unknown action');
+            }
+
+            // if a new node was created, we might be interested in it
+            // post diff hook
+            info.newNode = newNode;
+            this.postDiffApply(info);
+
+            return true;
+        },
+
+        // ===== Undo a diff =====
+
+        undo: function(tree, diffs) {
+            diffs = diffs.slice();
+            var dobj = this;
+            if (!diffs.length) {
+                diffs = [diffs];
+            }
+            diffs.reverse();
+            diffs.forEach(function(diff) {
+                dobj.undoDiff(tree, diff);
+            });
+        },
+        undoDiff: function(tree, diff) {
+
+            switch (diff.action) {
+                case 'addAttribute':
+                    diff.action = 'removeAttribute';
+                    this.applyDiff(tree, diff);
+                    break;
+                case 'modifyAttribute':
+                    swap(diff, 'oldValue', 'newValue');
+                    this.applyDiff(tree, diff);
+                    break;
+                case 'removeAttribute':
+                    diff.action = 'addAttribute';
+                    this.applyDiff(tree, diff);
+                    break;
+                case 'modifyTextElement':
+                    swap(diff, 'oldValue', 'newValue');
+                    this.applyDiff(tree, diff);
+                    break;
+                case 'modifyValue':
+                    swap(diff, 'oldValue', 'newValue');
+                    this.applyDiff(tree, diff);
+                    break;
+                case 'modifyComment':
+                    swap(diff, 'oldValue', 'newValue');
+                    this.applyDiff(tree, diff);
+                    break;
+                case 'modifyChecked':
+                    swap(diff, 'oldValue', 'newValue');
+                    this.applyDiff(tree, diff);
+                    break;
+                case 'modifySelected':
+                    swap(diff, 'oldValue', 'newValue');
+                    this.applyDiff(tree, diff);
+                    break;
+                case 'replaceElement':
+                    swap(diff, 'oldValue', 'newValue');
+                    this.applyDiff(tree, diff);
+                    break;
+                case 'relocateGroup':
+                    swap(diff, 'from', 'to');
+                    this.applyDiff(tree, diff);
+                    break;
+                case 'removeElement':
+                    diff.action = 'addElement';
+                    this.applyDiff(tree, diff);
+                    break;
+                case 'addElement':
+                    diff.action = 'removeElement';
+                    this.applyDiff(tree, diff);
+                    break;
+                case 'removeTextElement':
+                    diff.action = 'addTextElement';
+                    this.applyDiff(tree, diff);
+                    break;
+                case 'addTextElement':
+                    diff.action = 'removeTextElement';
+                    this.applyDiff(tree, diff);
+                    break;
+                default:
+                    console.log('unknown action');
+            }
+
+        }
+    };
+
+    if (typeof exports !== 'undefined') {
+        if (typeof module !== 'undefined' && module.exports) {
+            exports = module.exports = diffDOM;
+        }
+        exports.diffDOM = diffDOM;
+    } else {
+        // `window` in the browser, or `exports` on the server
+        this.diffDOM = diffDOM;
+    }
+
+}.call(this));