diff --git a/src/components/script/dom/bindings/error.rs b/src/components/script/dom/bindings/error.rs
index da30f40588b..aa4c84cd981 100644
--- a/src/components/script/dom/bindings/error.rs
+++ b/src/components/script/dom/bindings/error.rs
@@ -9,6 +9,7 @@ use js::glue::{ReportError};
 
 #[deriving(Show)]
 pub enum Error {
+    IndexSize,
     FailureUnknown,
     NotFound,
     HierarchyRequest,
diff --git a/src/components/script/dom/characterdata.rs b/src/components/script/dom/characterdata.rs
index f7b1afabde0..3cc503a50fd 100644
--- a/src/components/script/dom/characterdata.rs
+++ b/src/components/script/dom/characterdata.rs
@@ -6,7 +6,7 @@
 
 use dom::bindings::codegen::InheritTypes::CharacterDataDerived;
 use dom::bindings::js::JS;
-use dom::bindings::error::{Fallible, ErrorResult};
+use dom::bindings::error::{Fallible, ErrorResult, IndexSize};
 use dom::bindings::utils::{Reflectable, Reflector};
 use dom::document::Document;
 use dom::eventtarget::{EventTarget, NodeTargetTypeId};
@@ -59,6 +59,32 @@ impl CharacterData {
         self.data.push_str(arg);
         Ok(())
     }
+
+    pub fn InsertData(&mut self, offset: u32, arg: DOMString) -> ErrorResult {
+        self.ReplaceData(offset, 0, arg)
+    }
+
+    pub fn DeleteData(&mut self, offset: u32, count: u32) -> ErrorResult {
+        self.ReplaceData(offset, count, ~"")
+    }
+
+    pub fn ReplaceData(&mut self, offset: u32, count: u32, arg: DOMString) -> ErrorResult {
+        let length = self.data.len() as u32;
+        if offset > length {
+            return Err(IndexSize);
+        }
+        let count = if offset + count > length {
+            length - offset
+        } else {
+            count
+        };
+        let mut data = self.data.slice(0, offset as uint).to_owned();
+        data.push_str(arg);
+        data.push_str(self.data.slice((offset + count) as uint, length as uint));
+        self.data = data;
+        // FIXME: Once we have `Range`, we should implement step7 to step11
+        Ok(())
+    }
 }
 
 impl Reflectable for CharacterData {
diff --git a/src/components/script/dom/webidls/CharacterData.webidl b/src/components/script/dom/webidls/CharacterData.webidl
index 88c6c135a0c..00085fcc6b0 100644
--- a/src/components/script/dom/webidls/CharacterData.webidl
+++ b/src/components/script/dom/webidls/CharacterData.webidl
@@ -17,6 +17,12 @@ interface CharacterData : Node {
   DOMString substringData(unsigned long offset, unsigned long count);
   [Throws]
   void appendData(DOMString data);
+  [Throws]
+  void insertData(unsigned long offset, DOMString data);
+  [Throws]
+  void deleteData(unsigned long offset, unsigned long count);
+  [Throws]
+  void replaceData(unsigned long offset, unsigned long count, DOMString data);
 };
 
 //CharacterData implements ChildNode;