diff --git a/README.md b/README.md
index 3f6e86f..04a74b7 100644
--- a/README.md
+++ b/README.md
@@ -37,8 +37,8 @@ Coming soon...
 ## TODOs
 
 *    Implement NextUntil() and PrevUntil().
-*    Check each method, make sure it uses only ElementNodes except when explicitly specified (i.e.: `Contents()`). Cascadia's selectors act only on elements.
-*    Tests to validate that all methods returning a new `*Selection` "rollback" correctly to the previous Selection when calling `.End()`.
+*    Fix Prev...() functions to return nodes in the same order as jQuery (starting with the immediately preceding node, up until first child of the parent).
+*    Tests to validate that all methods returning a new `*Selection` "rollback" correctly to the previous Selection when calling `.End()`. Done for array, expand and filter.
 *    Benchmarks so that future changes have a baseline to compare to.
 *    Add jQuery's `Closest()`? Other missing functions?
 *    Support negative indices in `Slice()`, like jQuery.
diff --git a/array.go b/array.go
index 2888c08..412f027 100644
--- a/array.go
+++ b/array.go
@@ -47,20 +47,8 @@ func (this *Selection) Get(index int) *html.Node {
 // Index() returns the position of the first element within the Selection object
 // relative to its sibling elements.
 func (this *Selection) Index() int {
-	// TODO : Eventually refactor with prevAll(), like jQuery's code
 	if len(this.Nodes) > 0 {
-		n := this.Nodes[0]
-		if p := n.Parent; p != nil {
-			var i = 0
-			for _, c := range p.Child {
-				if c == n {
-					// This is the index of the element
-					return i
-				} else if c.Type == html.ElementNode {
-					i++
-				}
-			}
-		}
+		return newSingleSelection(this.Nodes[0], this.document).PrevAll().Length()
 	}
 	return -1
 }
diff --git a/array_test.go b/array_test.go
index 0390cf3..8f3c077 100644
--- a/array_test.go
+++ b/array_test.go
@@ -14,6 +14,12 @@ func TestFirstEmpty(t *testing.T) {
 	Doc().Root.Find(".pvk-zzcontentzz").First()
 }
 
+func TestFirstRollback(t *testing.T) {
+	sel := Doc().Root.Find(".pvk-content")
+	sel2 := sel.First().End()
+	AssertEqual(t, sel, sel2)
+}
+
 func TestLast(t *testing.T) {
 	sel := Doc().Root.Find(".pvk-content").Last()
 	AssertLength(t, sel.Nodes, 1)
@@ -25,6 +31,12 @@ func TestLast(t *testing.T) {
 	}
 }
 
+func TestLastRollback(t *testing.T) {
+	sel := Doc().Root.Find(".pvk-content")
+	sel2 := sel.Last().End()
+	AssertEqual(t, sel, sel2)
+}
+
 func TestEq(t *testing.T) {
 	sel := Doc().Root.Find(".pvk-content").Eq(1)
 	AssertLength(t, sel.Nodes, 1)
@@ -41,6 +53,12 @@ func TestEqNegative(t *testing.T) {
 	}
 }
 
+func TestEqRollback(t *testing.T) {
+	sel := Doc().Root.Find(".pvk-content")
+	sel2 := sel.Eq(1).End()
+	AssertEqual(t, sel, sel2)
+}
+
 func TestSlice(t *testing.T) {
 	sel := Doc().Root.Find(".pvk-content").Slice(0, 2)
 
@@ -52,6 +70,12 @@ func TestSliceOutOfBounds(t *testing.T) {
 	Doc().Root.Find(".pvk-content").Slice(2, 12)
 }
 
+func TestSliceRollback(t *testing.T) {
+	sel := Doc().Root.Find(".pvk-content")
+	sel2 := sel.Slice(0, 2).End()
+	AssertEqual(t, sel, sel2)
+}
+
 func TestGet(t *testing.T) {
 	sel := Doc().Root.Find(".pvk-content")
 	node := sel.Get(1)
diff --git a/doc.go b/doc.go
index 81a73e5..482953a 100644
--- a/doc.go
+++ b/doc.go
@@ -51,6 +51,11 @@ The various methods are split into files based on the category of behavior:
     - Last()
     - Slice()
 
+* expand.go : methods that expand or augment the selection's set.
+    - Add...()
+    - AndSelf()
+    - Union(), which is an alias for AddSelection()
+
 * filter.go : filtering methods, that reduce the selection's set.
     - End()
     - Filter...()
@@ -58,15 +63,9 @@ The various methods are split into files based on the category of behavior:
     - Intersection(), which is an alias of FilterSelection()
     - Not...()
 
-* expand.go : methods that expand or augment the selection's set.
-    - Add...()
-    - AndSelf()
-    - Union(), which is an alias for AddSelection()
-
-* query.go : methods that query, or reflect, a node's identity.
-    - Contains()
-    - HasClass()
-    - Is...()
+* iteration.go : methods to loop over the selection's nodes.
+    - Each()
+    - Map()
 
 * property.go : methods that inspect and get the node's properties values.
     - Attr()
@@ -75,6 +74,11 @@ The various methods are split into files based on the category of behavior:
     - Size(), which is an alias for Length()
     - Text()
 
+* query.go : methods that query, or reflect, a node's identity.
+    - Contains()
+    - HasClass()
+    - Is...()
+
 * traversal.go : methods to traverse the HTML document tree.
     - Children...()
     - Contents()
@@ -84,21 +88,8 @@ The various methods are split into files based on the category of behavior:
     - Prev...()
     - Siblings...()
 
-* iteration.go : methods to loop over the selection's nodes.
-    - Each()
-    - Map()
-
 * type.go : definition of the types exposed by GoQuery.
     - Document
     - Selection
 */
 package goquery
-
-// DONE array.go : Positional Manipulation: First(), Last(), Eq(), Get(), Index(), Slice()
-// DONE filter.go : Filtering: Filter(), Not(), Has(), End()
-// DONE expand.go : "Expanding": Add(), AndSelf()
-// DONE query.go : Reflect (query) node: Is(), Contains(), HasClass()
-// DONE property.go : Inspect node: Html(), Text(), Attr(), Length(), Size()
-// traversal.go : Traversal: Contents(), Find(), Children(), Parents...(), Next...(), Prev...(), Siblings()
-// DONE iteration.go : Iteration: Each(), Map()
-// DONE type.go : Selection and Document
diff --git a/expand_test.go b/expand_test.go
index 37ea247..4e8f5ec 100644
--- a/expand_test.go
+++ b/expand_test.go
@@ -9,6 +9,12 @@ func TestAdd(t *testing.T) {
 	AssertLength(t, sel.Nodes, 19)
 }
 
+func TestAddRollback(t *testing.T) {
+	sel := Doc().Root.Find(".pvk-content")
+	sel2 := sel.Add("a").End()
+	AssertEqual(t, sel, sel2)
+}
+
 func TestAddSelection(t *testing.T) {
 	sel := Doc().Root.Find("div.row-fluid")
 	sel2 := Doc().Root.Find("a")
@@ -24,6 +30,13 @@ func TestAddSelectionNil(t *testing.T) {
 	AssertLength(t, sel.Nodes, 9)
 }
 
+func TestAddSelectionRollback(t *testing.T) {
+	sel := Doc().Root.Find(".pvk-content")
+	sel2 := sel.Find("a")
+	sel2 = sel.AddSelection(sel2).End()
+	AssertEqual(t, sel, sel2)
+}
+
 func TestAddNodes(t *testing.T) {
 	sel := Doc().Root.Find("div.pvk-gutter")
 	sel2 := Doc().Root.Find(".pvk-content")
@@ -36,7 +49,20 @@ func TestAddNodesNone(t *testing.T) {
 	AssertLength(t, sel.Nodes, 6)
 }
 
+func TestAddNodesRollback(t *testing.T) {
+	sel := Doc().Root.Find(".pvk-content")
+	sel2 := sel.Find("a")
+	sel2 = sel.AddNodes(sel2.Nodes...).End()
+	AssertEqual(t, sel, sel2)
+}
+
 func TestAndSelf(t *testing.T) {
 	sel := Doc().Root.Find(".span12").Last().AndSelf()
 	AssertLength(t, sel.Nodes, 2)
 }
+
+func TestAndSelfRollback(t *testing.T) {
+	sel := Doc().Root.Find(".pvk-content")
+	sel2 := sel.Find("a").AndSelf().End().End()
+	AssertEqual(t, sel, sel2)
+}
diff --git a/filter_test.go b/filter_test.go
index eb497fa..9df4661 100644
--- a/filter_test.go
+++ b/filter_test.go
@@ -14,6 +14,12 @@ func TestFilterNone(t *testing.T) {
 	AssertLength(t, sel.Nodes, 0)
 }
 
+func TestFilterRollback(t *testing.T) {
+	sel := Doc().Root.Find(".pvk-content")
+	sel2 := sel.Filter(".alert").End()
+	AssertEqual(t, sel, sel2)
+}
+
 func TestFilterFunction(t *testing.T) {
 	sel := Doc().Root.Find(".pvk-content").FilterFunction(func(i int, s *Selection) bool {
 		return i > 0
@@ -21,12 +27,26 @@ func TestFilterFunction(t *testing.T) {
 	AssertLength(t, sel.Nodes, 2)
 }
 
+func TestFilterFunctionRollback(t *testing.T) {
+	sel := Doc().Root.Find(".pvk-content")
+	sel2 := sel.FilterFunction(func(i int, s *Selection) bool {
+		return i > 0
+	}).End()
+	AssertEqual(t, sel, sel2)
+}
+
 func TestFilterNode(t *testing.T) {
 	sel := Doc().Root.Find(".pvk-content")
 	sel2 := sel.FilterNodes(sel.Nodes[2])
 	AssertLength(t, sel2.Nodes, 1)
 }
 
+func TestFilterNodeRollback(t *testing.T) {
+	sel := Doc().Root.Find(".pvk-content")
+	sel2 := sel.FilterNodes(sel.Nodes[2]).End()
+	AssertEqual(t, sel, sel2)
+}
+
 func TestFilterSelection(t *testing.T) {
 	sel := Doc().Root.Find(".link")
 	sel2 := Doc().Root.Find("a[ng-click]")
@@ -34,6 +54,13 @@ func TestFilterSelection(t *testing.T) {
 	AssertLength(t, sel3.Nodes, 1)
 }
 
+func TestFilterSelectionRollback(t *testing.T) {
+	sel := Doc().Root.Find(".link")
+	sel2 := Doc().Root.Find("a[ng-click]")
+	sel2 = sel.FilterSelection(sel2).End()
+	AssertEqual(t, sel, sel2)
+}
+
 func TestFilterSelectionNil(t *testing.T) {
 	var sel2 *Selection
 
@@ -47,6 +74,12 @@ func TestNot(t *testing.T) {
 	AssertLength(t, sel.Nodes, 1)
 }
 
+func TestNotRollback(t *testing.T) {
+	sel := Doc().Root.Find(".span12")
+	sel2 := sel.Not(".alert").End()
+	AssertEqual(t, sel, sel2)
+}
+
 func TestNotNone(t *testing.T) {
 	sel := Doc().Root.Find(".span12").Not(".zzalert")
 	AssertLength(t, sel.Nodes, 2)
@@ -59,12 +92,26 @@ func TestNotFunction(t *testing.T) {
 	AssertLength(t, sel.Nodes, 1)
 }
 
+func TestNotFunctionRollback(t *testing.T) {
+	sel := Doc().Root.Find(".pvk-content")
+	sel2 := sel.NotFunction(func(i int, s *Selection) bool {
+		return i > 0
+	}).End()
+	AssertEqual(t, sel, sel2)
+}
+
 func TestNotNode(t *testing.T) {
 	sel := Doc().Root.Find(".pvk-content")
 	sel2 := sel.NotNodes(sel.Nodes[2])
 	AssertLength(t, sel2.Nodes, 2)
 }
 
+func TestNotNodeRollback(t *testing.T) {
+	sel := Doc().Root.Find(".pvk-content")
+	sel2 := sel.NotNodes(sel.Nodes[2]).End()
+	AssertEqual(t, sel, sel2)
+}
+
 func TestNotSelection(t *testing.T) {
 	sel := Doc().Root.Find(".link")
 	sel2 := Doc().Root.Find("a[ng-click]")
@@ -72,18 +119,38 @@ func TestNotSelection(t *testing.T) {
 	AssertLength(t, sel3.Nodes, 6)
 }
 
+func TestNotSelectionRollback(t *testing.T) {
+	sel := Doc().Root.Find(".link")
+	sel2 := Doc().Root.Find("a[ng-click]")
+	sel2 = sel.NotSelection(sel2).End()
+	AssertEqual(t, sel, sel2)
+}
+
 func TestIntersection(t *testing.T) {
 	sel := Doc().Root.Find(".pvk-gutter")
 	sel2 := Doc().Root.Find("div").Intersection(sel)
 	AssertLength(t, sel2.Nodes, 6)
 }
 
+func TestIntersectionRollback(t *testing.T) {
+	sel := Doc().Root.Find(".pvk-gutter")
+	sel2 := Doc().Root.Find("div")
+	sel2 = sel.Intersection(sel2).End()
+	AssertEqual(t, sel, sel2)
+}
+
 func TestHas(t *testing.T) {
 	sel := Doc().Root.Find(".container-fluid").Has(".center-content")
 	AssertLength(t, sel.Nodes, 2)
 	// Has() returns the high-level .container-fluid div, and the one that is the immediate parent of center-content
 }
 
+func TestHasRollback(t *testing.T) {
+	sel := Doc().Root.Find(".container-fluid")
+	sel2 := sel.Has(".center-content").End()
+	AssertEqual(t, sel, sel2)
+}
+
 func TestHasNodes(t *testing.T) {
 	sel := Doc().Root.Find(".container-fluid")
 	sel2 := Doc().Root.Find(".center-content")
@@ -92,6 +159,13 @@ func TestHasNodes(t *testing.T) {
 	// Has() returns the high-level .container-fluid div, and the one that is the immediate parent of center-content
 }
 
+func TestHasNodesRollback(t *testing.T) {
+	sel := Doc().Root.Find(".container-fluid")
+	sel2 := Doc().Root.Find(".center-content")
+	sel2 = sel.HasNodes(sel2.Nodes...).End()
+	AssertEqual(t, sel, sel2)
+}
+
 func TestHasSelection(t *testing.T) {
 	sel := Doc().Root.Find("p")
 	sel2 := Doc().Root.Find("small")
@@ -99,6 +173,13 @@ func TestHasSelection(t *testing.T) {
 	AssertLength(t, sel.Nodes, 1)
 }
 
+func TestHasSelectionRollback(t *testing.T) {
+	sel := Doc().Root.Find("p")
+	sel2 := Doc().Root.Find("small")
+	sel2 = sel.HasSelection(sel2).End()
+	AssertEqual(t, sel, sel2)
+}
+
 func TestEnd(t *testing.T) {
 	sel := Doc().Root.Find("p").Has("small").End()
 	AssertLength(t, sel.Nodes, 4)
diff --git a/iteration.go b/iteration.go
index 17a5ee7..ff07f29 100644
--- a/iteration.go
+++ b/iteration.go
@@ -1,7 +1,7 @@
 package goquery
 
 // Each() iterates over a Selection object, executing a function for each
-// matched element.
+// matched element. It returns the current Selection object.
 func (this *Selection) Each(f func(int, *Selection)) *Selection {
 	for i, n := range this.Nodes {
 		f(i, newSingleSelection(n, this.document))
diff --git a/property.go b/property.go
index c793cba..a29c208 100644
--- a/property.go
+++ b/property.go
@@ -20,6 +20,7 @@ func (this *Selection) Attr(attrName string) (val string, exists bool) {
 func (this *Selection) Text() string {
 	var buf bytes.Buffer
 
+	// Slightly optimized vs calling Each(): no single selection object created
 	for _, n := range this.Nodes {
 		buf.WriteString(getNodeText(n))
 	}
@@ -37,7 +38,7 @@ func (this *Selection) Length() int {
 }
 
 // Html() gets the HTML contents of the first element in the set of matched
-// elements.
+// elements. It includes text and comment nodes.
 func (this *Selection) Html() (ret string, e error) {
 	// Since there is no .innerHtml, the HTML content must be re-created from
 	// the nodes usint html.Render().
@@ -59,7 +60,6 @@ func (this *Selection) Html() (ret string, e error) {
 // Get the specified node's text content.
 func getNodeText(node *html.Node) string {
 	if node.Type == html.TextNode {
-		//ret = strings.Trim(node.Data, " \t\r\n")
 		// Keep newlines and spaces, like jQuery
 		return node.Data
 	} else if len(node.Child) > 0 {
diff --git a/query.go b/query.go
index 3a7bc62..daf0cef 100644
--- a/query.go
+++ b/query.go
@@ -39,19 +39,19 @@ func (this *Selection) Is(selector string) bool {
 	return false
 }
 
-// Is() checks the current matched set of elements against a predicate and
+// IsFunction() checks the current matched set of elements against a predicate and
 // returns true if at least one of these elements matches.
 func (this *Selection) IsFunction(f func(int, *Selection) bool) bool {
 	return this.FilterFunction(f).Length() > 0
 }
 
-// Is() checks the current matched set of elements against a Selection object
+// IsSelection() checks the current matched set of elements against a Selection object
 // and returns true if at least one of these elements matches.
 func (this *Selection) IsSelection(s *Selection) bool {
 	return this.FilterSelection(s).Length() > 0
 }
 
-// Is() checks the current matched set of elements against the specified nodes
+// IsNodes() checks the current matched set of elements against the specified nodes
 // and returns true if at least one of these elements matches.
 func (this *Selection) IsNodes(nodes ...*html.Node) bool {
 	return this.FilterNodes(nodes...).Length() > 0
diff --git a/traversal.go b/traversal.go
index 3e48cb1..4ff5eff 100644
--- a/traversal.go
+++ b/traversal.go
@@ -10,11 +10,13 @@ type siblingType int
 // Sibling type, used internally when iterating over children at the same
 // level (siblings) to specify which nodes are requested.
 const (
-	siblintPrevAll siblingType = iota - 2
+	siblingPrevUntil siblingType = iota - 3
+	siblingPrevAll
 	siblingPrev
 	siblingAll
 	siblingNext
 	siblingNextAll
+	siblingNextUntil
 	siblingAllIncludingNonElements
 )
 
@@ -206,14 +208,14 @@ func (this *Selection) PrevFiltered(selector string) *Selection {
 // PrevAll() gets all the preceding siblings of each element in the
 // Selection. It returns a new Selection object containing the matched elements.
 func (this *Selection) PrevAll() *Selection {
-	return pushStack(this, getSiblingNodes(this.Nodes, siblintPrevAll))
+	return pushStack(this, getSiblingNodes(this.Nodes, siblingPrevAll))
 }
 
 // PrevAllFiltered() gets all the preceding siblings of each element in the
 // Selection filtered by a selector. It returns a new Selection object
 // containing the matched elements.
 func (this *Selection) PrevAllFiltered(selector string) *Selection {
-	return filterAndPush(this, getSiblingNodes(this.Nodes, siblintPrevAll), selector)
+	return filterAndPush(this, getSiblingNodes(this.Nodes, siblingPrevAll), selector)
 }
 
 // Filter and push filters the nodes based on a selector, and pushes the results
@@ -314,7 +316,11 @@ func getChildrenWithSiblingType(parent *html.Node, st siblingType, skipNode *htm
 
 			// If child is not the current node, check if sibling type requires
 			// to add it to the result.
-			if c != skipNode && (st == siblingAll || st == siblingAllIncludingNonElements || (st == siblintPrevAll && !nFound) || (st == siblingNextAll && nFound)) {
+			if c != skipNode &&
+				(st == siblingAll ||
+					st == siblingAllIncludingNonElements ||
+					(st == siblingPrevAll && !nFound) ||
+					(st == siblingNextAll && nFound)) {
 				result = append(result, c)
 			}
 		}
diff --git a/type_test.go b/type_test.go
index 00a7510..da55224 100644
--- a/type_test.go
+++ b/type_test.go
@@ -37,6 +37,12 @@ func AssertPanic(t *testing.T) {
 	}
 }
 
+func AssertEqual(t *testing.T, s1 *Selection, s2 *Selection) {
+	if s1 != s2 {
+		t.Error("Expected selection objects to be the same.")
+	}
+}
+
 func EnsureDocLoaded() {
 	if f, e := os.Open("./testdata/page.html"); e != nil {
 		panic(e.Error())