diff --git a/components/script/dom/element.rs b/components/script/dom/element.rs
index d3b5b1946aa..1268c75f5a1 100644
--- a/components/script/dom/element.rs
+++ b/components/script/dom/element.rs
@@ -15,7 +15,7 @@ use dom::bindings::codegen::Bindings::NamedNodeMapBinding::NamedNodeMapMethods;
 use dom::bindings::codegen::InheritTypes::{ElementDerived, HTMLInputElementDerived};
 use dom::bindings::codegen::InheritTypes::{HTMLTableCellElementDerived, NodeCast};
 use dom::bindings::js::{MutNullableJS, JS, JSRef, Temporary, TemporaryPushable};
-use dom::bindings::js::{OptionalSettable, OptionalRootable, Root};
+use dom::bindings::js::{OptionalRootable, Root};
 use dom::bindings::utils::{Reflectable, Reflector};
 use dom::bindings::error::{ErrorResult, Fallible, NamespaceError, InvalidCharacter, Syntax};
 use dom::bindings::utils::{QName, Name, InvalidXMLName, xml_name_type};
@@ -708,25 +708,19 @@ impl<'a> ElementMethods for JSRef<'a, Element> {
 
     // http://dom.spec.whatwg.org/#dom-element-classlist
     fn ClassList(self) -> Temporary<DOMTokenList> {
-        if self.class_list.get().is_none() {
-            let class_list = DOMTokenList::new(self, &atom!("class"));
-            self.class_list.assign(Some(class_list));
-        }
-        self.class_list.get().unwrap()
+        self.class_list.or_init(|| DOMTokenList::new(self, &atom!("class")))
     }
 
     // http://dom.spec.whatwg.org/#dom-element-attributes
     fn Attributes(self) -> Temporary<NamedNodeMap> {
-        if self.attr_list.get().is_none() {
+        self.attr_list.or_init(|| {
             let doc = {
                 let node: JSRef<Node> = NodeCast::from_ref(self);
                 node.owner_doc().root()
             };
             let window = doc.window().root();
-            let list = NamedNodeMap::new(*window, self);
-            self.attr_list.assign(Some(list));
-        }
-        self.attr_list.get().unwrap()
+            NamedNodeMap::new(*window, self)
+        })
     }
 
     // http://dom.spec.whatwg.org/#dom-element-getattribute
diff --git a/components/script/dom/htmlanchorelement.rs b/components/script/dom/htmlanchorelement.rs
index 2b1d615a4bf..c712ddad60e 100644
--- a/components/script/dom/htmlanchorelement.rs
+++ b/components/script/dom/htmlanchorelement.rs
@@ -117,11 +117,8 @@ impl<'a> HTMLAnchorElementMethods for JSRef<'a, HTMLAnchorElement> {
     }
 
     fn RelList(self) -> Temporary<DOMTokenList> {
-        if self.rel_list.get().is_none() {
-            let element: JSRef<Element> = ElementCast::from_ref(self);
-            let rel_list = DOMTokenList::new(element, &atom!("rel"));
-            self.rel_list.assign(Some(rel_list));
-        }
-        self.rel_list.get().unwrap()
+        self.rel_list.or_init(|| {
+            DOMTokenList::new(ElementCast::from_ref(self), &atom!("rel"))
+        })
     }
 }
diff --git a/components/script/dom/htmlareaelement.rs b/components/script/dom/htmlareaelement.rs
index ffc2eb2b23a..fc4c29bc085 100644
--- a/components/script/dom/htmlareaelement.rs
+++ b/components/script/dom/htmlareaelement.rs
@@ -11,7 +11,6 @@ use dom::bindings::js::{MutNullableJS, JSRef, Temporary};
 use dom::bindings::utils::{Reflectable, Reflector};
 use dom::document::Document;
 use dom::domtokenlist::DOMTokenList;
-use dom::element::Element;
 use dom::element::HTMLAreaElementTypeId;
 use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
@@ -73,11 +72,8 @@ impl Reflectable for HTMLAreaElement {
 
 impl<'a> HTMLAreaElementMethods for JSRef<'a, HTMLAreaElement> {
     fn RelList(self) -> Temporary<DOMTokenList> {
-        if self.rel_list.get().is_none() {
-            let element: JSRef<Element> = ElementCast::from_ref(self);
-            let rel_list = DOMTokenList::new(element, &atom!("rel"));
-            self.rel_list.assign(Some(rel_list));
-        }
-        self.rel_list.get().unwrap()
+        self.rel_list.or_init(|| {
+            DOMTokenList::new(ElementCast::from_ref(self), &atom!("rel"))
+        })
     }
 }
diff --git a/components/script/dom/htmllinkelement.rs b/components/script/dom/htmllinkelement.rs
index acec40b942c..e1eeff03ad8 100644
--- a/components/script/dom/htmllinkelement.rs
+++ b/components/script/dom/htmllinkelement.rs
@@ -146,11 +146,8 @@ impl Reflectable for HTMLLinkElement {
 
 impl<'a> HTMLLinkElementMethods for JSRef<'a, HTMLLinkElement> {
     fn RelList(self) -> Temporary<DOMTokenList> {
-        if self.rel_list.get().is_none() {
-            let element: JSRef<Element> = ElementCast::from_ref(self);
-            let rel_list = DOMTokenList::new(element, &atom!("rel"));
-            self.rel_list.assign(Some(rel_list));
-        }
-        self.rel_list.get().unwrap()
+        self.rel_list.or_init(|| {
+            DOMTokenList::new(ElementCast::from_ref(self), &atom!("rel"))
+        })
     }
 }
diff --git a/components/script/dom/workerglobalscope.rs b/components/script/dom/workerglobalscope.rs
index 51e90d4c3dc..c5e87e90a83 100644
--- a/components/script/dom/workerglobalscope.rs
+++ b/components/script/dom/workerglobalscope.rs
@@ -6,7 +6,7 @@ use dom::bindings::codegen::Bindings::WorkerGlobalScopeBinding::WorkerGlobalScop
 use dom::bindings::codegen::Bindings::FunctionBinding::Function;
 use dom::bindings::error::{ErrorResult, Fallible, Syntax, Network, FailureUnknown};
 use dom::bindings::global;
-use dom::bindings::js::{MutNullableJS, JSRef, Temporary, OptionalSettable};
+use dom::bindings::js::{MutNullableJS, JSRef, Temporary};
 use dom::bindings::utils::{Reflectable, Reflector};
 use dom::console::Console;
 use dom::eventtarget::{EventTarget, WorkerGlobalScopeTypeId};
@@ -93,11 +93,9 @@ impl<'a> WorkerGlobalScopeMethods for JSRef<'a, WorkerGlobalScope> {
     }
 
     fn Location(self) -> Temporary<WorkerLocation> {
-        if self.location.get().is_none() {
-            let location = WorkerLocation::new(self, self.worker_url.clone());
-            self.location.assign(Some(location));
-        }
-        self.location.get().unwrap()
+        self.location.or_init(|| {
+            WorkerLocation::new(self, self.worker_url.clone())
+        })
     }
 
     fn ImportScripts(self, url_strings: Vec<DOMString>) -> ErrorResult {
@@ -133,19 +131,11 @@ impl<'a> WorkerGlobalScopeMethods for JSRef<'a, WorkerGlobalScope> {
     }
 
     fn Navigator(self) -> Temporary<WorkerNavigator> {
-        if self.navigator.get().is_none() {
-            let navigator = WorkerNavigator::new(self);
-            self.navigator.assign(Some(navigator));
-        }
-        self.navigator.get().unwrap()
+        self.navigator.or_init(|| WorkerNavigator::new(self))
     }
 
     fn Console(self) -> Temporary<Console> {
-        if self.console.get().is_none() {
-            let console = Console::new(global::Worker(self));
-            self.console.assign(Some(console));
-        }
-        self.console.get().unwrap()
+        self.console.or_init(|| Console::new(global::Worker(self)))
     }
 
     fn Btoa(self, btoa: DOMString) -> Fallible<DOMString> {