diff --git a/src/CompositionHelper.ts b/src/CompositionHelper.ts
index 3bf829e5..8a29ed72 100644
--- a/src/CompositionHelper.ts
+++ b/src/CompositionHelper.ts
@@ -3,211 +3,228 @@
  * Copyright (c) 2014-2016, SourceLair Private Company (www.sourcelair.com (MIT License)
  */
 
-/**
- * Encapsulates the logic for handling compositionstart, compositionupdate and compositionend
- * events, displaying the in-progress composition to the UI and forwarding the final composition
- * to the handler.
- * @param {HTMLTextAreaElement} textarea The textarea that xterm uses for input.
- * @param {HTMLElement} compositionView The element to display the in-progress composition in.
- * @param {Terminal} terminal The Terminal to forward the finished composition to.
- */
-function CompositionHelper(textarea, compositionView, terminal) {
-  this.textarea = textarea;
-  this.compositionView = compositionView;
-  this.terminal = terminal;
+import { ITerminal } from './Interfaces';
 
-  // Whether input composition is currently happening, eg. via a mobile keyboard, speech input
-  // or IME. This variable determines whether the compositionText should be displayed on the UI.
-  this.isComposing = false;
-
-  // The input currently being composed, eg. via a mobile keyboard, speech input or IME.
-  this.compositionText = null;
-
-  // The position within the input textarea's value of the current composition.
-  this.compositionPosition = { start: null, end: null };
-
-  // Whether a composition is in the process of being sent, setting this to false will cancel
-  // any in-progress composition.
-  this.isSendingComposition = false;
+interface IPosition {
+  start: number;
+  end: number;
 }
 
-/**
- * Handles the compositionstart event, activating the composition view.
- */
-CompositionHelper.prototype.compositionstart = function() {
-  this.isComposing = true;
-  this.compositionPosition.start = this.textarea.value.length;
-  this.compositionView.textContent = '';
-  this.compositionView.classList.add('active');
-};
+export class CompositionHelper {
+  /**
+   * Whether input composition is currently happening, eg. via a mobile keyboard, speech input or
+   * IME. This variable determines whether the compositionText should be displayed on the UI.
+   */
+  private isComposing: boolean;
 
-/**
- * Handles the compositionupdate event, updating the composition view.
- * @param {CompositionEvent} ev The event.
- */
-CompositionHelper.prototype.compositionupdate = function(ev) {
-  this.compositionView.textContent = ev.data;
-  this.updateCompositionElements();
-  var self = this;
-  setTimeout(function() {
-    self.compositionPosition.end = self.textarea.value.length;
-  }, 0);
-};
+  /**
+   * The position within the input textarea's value of the current composition.
+   */
+  private compositionPosition: IPosition;;
 
-/**
- * Handles the compositionend event, hiding the composition view and sending the composition to
- * the handler.
- */
-CompositionHelper.prototype.compositionend = function() {
-  this.finalizeComposition(true);
-};
+  /**
+   * Whether a composition is in the process of being sent, setting this to false will cancel any
+   * in-progress composition.
+   */
+  private isSendingComposition: boolean;
 
-/**
- * Handles the keydown event, routing any necessary events to the CompositionHelper functions.
- * @return Whether the Terminal should continue processing the keydown event.
- */
-CompositionHelper.prototype.keydown = function(ev) {
-  if (this.isComposing || this.isSendingComposition) {
-    if (ev.keyCode === 229) {
-      // Continue composing if the keyCode is the "composition character"
-      return false;
-    } else if (ev.keyCode === 16 || ev.keyCode === 17 || ev.keyCode === 18) {
-      // Continue composing if the keyCode is a modifier key
-      return false;
-    } else {
-      // Finish composition immediately. This is mainly here for the case where enter is
-      // pressed and the handler needs to be triggered before the command is executed.
-      this.finalizeComposition(false);
-    }
-  }
-
-  if (ev.keyCode === 229) {
-    // If the "composition character" is used but gets to this point it means a non-composition
-    // character (eg. numbers and punctuation) was pressed when the IME was active.
-    this.handleAnyTextareaChanges();
-    return false;
-  }
-
-  return true;
-};
-
-/**
- * Finalizes the composition, resuming regular input actions. This is called when a composition
- * is ending.
- * @param {boolean} waitForPropogation Whether to wait for events to propogate before sending
- *   the input. This should be false if a non-composition keystroke is entered before the
- *   compositionend event is triggered, such as enter, so that the composition is send before
- *   the command is executed.
- */
-CompositionHelper.prototype.finalizeComposition = function(waitForPropogation) {
-  this.compositionView.classList.remove('active');
-  this.isComposing = false;
-  this.clearTextareaPosition();
-
-  if (!waitForPropogation) {
-    // Cancel any delayed composition send requests and send the input immediately.
+  /**
+   * Encapsulates the logic for handling compositionstart, compositionupdate and compositionend
+   * events, displaying the in-progress composition to the UI and forwarding the final composition
+   * to the handler.
+   * @param textarea The textarea that xterm uses for input.
+   * @param compositionView The element to display the in-progress composition in.
+   * @param terminal The Terminal to forward the finished composition to.
+   */
+  constructor(
+    private textarea: HTMLTextAreaElement,
+    private compositionView: HTMLElement,
+    private terminal: ITerminal
+  ) {
+    this.isComposing = false;
     this.isSendingComposition = false;
-    var input = this.textarea.value.substring(this.compositionPosition.start, this.compositionPosition.end);
-    this.terminal.handler(input);
-  } else {
-    // Make a deep copy of the composition position here as a new compositionstart event may
-    // fire before the setTimeout executes.
-    var currentCompositionPosition = {
-      start: this.compositionPosition.start,
-      end: this.compositionPosition.end,
+    this.compositionPosition = { start: null, end: null };
+  }
+
+  /**
+   * Handles the compositionstart event, activating the composition view.
+   */
+  public compositionstart() {
+    this.isComposing = true;
+    this.compositionPosition.start = this.textarea.value.length;
+    this.compositionView.textContent = '';
+    this.compositionView.classList.add('active');
+  }
+
+  /**
+   * Handles the compositionupdate event, updating the composition view.
+   * @param {CompositionEvent} ev The event.
+   */
+  public compositionupdate(ev: CompositionEvent) {
+    this.compositionView.textContent = ev.data;
+    this.updateCompositionElements();
+    var self = this;
+    setTimeout(function() {
+      self.compositionPosition.end = self.textarea.value.length;
+    }, 0);
+  }
+
+  /**
+   * Handles the compositionend event, hiding the composition view and sending the composition to
+   * the handler.
+   */
+  public compositionend() {
+    this.finalizeComposition(true);
+  }
+
+  /**
+   * Handles the keydown event, routing any necessary events to the CompositionHelper functions.
+   * @param ev The keydown event.
+   * @return Whether the Terminal should continue processing the keydown event.
+   */
+  public keydown(ev: KeyboardEvent) {
+    if (this.isComposing || this.isSendingComposition) {
+      if (ev.keyCode === 229) {
+        // Continue composing if the keyCode is the "composition character"
+        return false;
+      } else if (ev.keyCode === 16 || ev.keyCode === 17 || ev.keyCode === 18) {
+        // Continue composing if the keyCode is a modifier key
+        return false;
+      } else {
+        // Finish composition immediately. This is mainly here for the case where enter is
+        // pressed and the handler needs to be triggered before the command is executed.
+        this.finalizeComposition(false);
+      }
     }
 
-    // Since composition* events happen before the changes take place in the textarea on most
-    // browsers, use a setTimeout with 0ms time to allow the native compositionend event to
-    // complete. This ensures the correct character is retrieved, this solution was used
-    // because:
-    // - The compositionend event's data property is unreliable, at least on Chromium
-    // - The last compositionupdate event's data property does not always accurately describe
-    //   the character, a counter example being Korean where an ending consonsant can move to
-    //   the following character if the following input is a vowel.
+    if (ev.keyCode === 229) {
+      // If the "composition character" is used but gets to this point it means a non-composition
+      // character (eg. numbers and punctuation) was pressed when the IME was active.
+      this.handleAnyTextareaChanges();
+      return false;
+    }
+
+    return true;
+  }
+
+  /**
+   * Finalizes the composition, resuming regular input actions. This is called when a composition
+   * is ending.
+   * @param waitForPropogation Whether to wait for events to propogate before sending
+   *   the input. This should be false if a non-composition keystroke is entered before the
+   *   compositionend event is triggered, such as enter, so that the composition is send before
+   *   the command is executed.
+   */
+  private finalizeComposition(waitForPropogation: boolean) {
+    this.compositionView.classList.remove('active');
+    this.isComposing = false;
+    this.clearTextareaPosition();
+
+    if (!waitForPropogation) {
+      // Cancel any delayed composition send requests and send the input immediately.
+      this.isSendingComposition = false;
+      var input = this.textarea.value.substring(this.compositionPosition.start, this.compositionPosition.end);
+      this.terminal.handler(input);
+    } else {
+      // Make a deep copy of the composition position here as a new compositionstart event may
+      // fire before the setTimeout executes.
+      var currentCompositionPosition = {
+        start: this.compositionPosition.start,
+        end: this.compositionPosition.end,
+      }
+
+      // Since composition* events happen before the changes take place in the textarea on most
+      // browsers, use a setTimeout with 0ms time to allow the native compositionend event to
+      // complete. This ensures the correct character is retrieved, this solution was used
+      // because:
+      // - The compositionend event's data property is unreliable, at least on Chromium
+      // - The last compositionupdate event's data property does not always accurately describe
+      //   the character, a counter example being Korean where an ending consonsant can move to
+      //   the following character if the following input is a vowel.
+      var self = this;
+      this.isSendingComposition = true;
+      setTimeout(function () {
+        // Ensure that the input has not already been sent
+        if (self.isSendingComposition) {
+          self.isSendingComposition = false;
+          var input;
+          if (self.isComposing) {
+            // Use the end position to get the string if a new composition has started.
+            input = self.textarea.value.substring(currentCompositionPosition.start, currentCompositionPosition.end);
+          } else {
+            // Don't use the end position here in order to pick up any characters after the
+            // composition has finished, for example when typing a non-composition character
+            // (eg. 2) after a composition character.
+            input = self.textarea.value.substring(currentCompositionPosition.start);
+          }
+          self.terminal.handler(input);
+        }
+      }, 0);
+    }
+  }
+
+  /**
+   * Apply any changes made to the textarea after the current event chain is allowed to complete.
+   * This should be called when not currently composing but a keydown event with the "composition
+   * character" (229) is triggered, in order to allow non-composition text to be entered when an
+   * IME is active.
+   */
+  private handleAnyTextareaChanges() {
+    var oldValue = this.textarea.value;
     var self = this;
-    this.isSendingComposition = true;
-    setTimeout(function () {
-      // Ensure that the input has not already been sent
-      if (self.isSendingComposition) {
-        self.isSendingComposition = false;
-        var input;
-        if (self.isComposing) {
-          // Use the end position to get the string if a new composition has started.
-          input = self.textarea.value.substring(currentCompositionPosition.start, currentCompositionPosition.end);
-        } else {
-          // Don't use the end position here in order to pick up any characters after the
-          // composition has finished, for example when typing a non-composition character
-          // (eg. 2) after a composition character.
-          input = self.textarea.value.substring(currentCompositionPosition.start);
+    setTimeout(function() {
+      // Ignore if a composition has started since the timeout
+      if (!self.isComposing) {
+        var newValue = self.textarea.value;
+        var diff = newValue.replace(oldValue, '');
+        if (diff.length > 0) {
+          self.terminal.handler(diff);
         }
-        self.terminal.handler(input);
       }
     }, 0);
   }
-};
 
-/**
- * Apply any changes made to the textarea after the current event chain is allowed to complete.
- * This should be called when not currently composing but a keydown event with the "composition
- * character" (229) is triggered, in order to allow non-composition text to be entered when an
- * IME is active.
- */
-CompositionHelper.prototype.handleAnyTextareaChanges = function() {
-  var oldValue = this.textarea.value;
-  var self = this;
-  setTimeout(function() {
-    // Ignore if a composition has started since the timeout
-    if (!self.isComposing) {
-      var newValue = self.textarea.value;
-      var diff = newValue.replace(oldValue, '');
-      if (diff.length > 0) {
-        self.terminal.handler(diff);
-      }
+  /**
+   * Positions the composition view on top of the cursor and the textarea just below it (so the
+   * IME helper dialog is positioned correctly).
+   * @param dontRecurse Whether to use setTimeout to recursively trigger another update, this is
+   *   necessary as the IME events across browsers are not consistently triggered.
+   */
+  public updateCompositionElements(dontRecurse?: boolean) {
+    if (!this.isComposing) {
+      return;
     }
-  }, 0);
-};
+    var cursor = <HTMLElement>this.terminal.element.querySelector('.terminal-cursor');
+    if (cursor) {
+      // Take .xterm-rows offsetTop into account as well in case it's positioned absolutely within
+      // the .xterm element.
+      var xtermRows = <HTMLElement>this.terminal.element.querySelector('.xterm-rows');
+      var cursorTop = xtermRows.offsetTop + cursor.offsetTop;
 
-/**
- * Positions the composition view on top of the cursor and the textarea just below it (so the
- * IME helper dialog is positioned correctly).
- */
-CompositionHelper.prototype.updateCompositionElements = function(dontRecurse) {
-  if (!this.isComposing) {
-    return;
-  }
-  var cursor = this.terminal.element.querySelector('.terminal-cursor');
-  if (cursor) {
-    // Take .xterm-rows offsetTop into account as well in case it's positioned absolutely within
-    // the .xterm element.
-    var xtermRows = this.terminal.element.querySelector('.xterm-rows');
-    var cursorTop = xtermRows.offsetTop + cursor.offsetTop;
+      this.compositionView.style.left = cursor.offsetLeft + 'px';
+      this.compositionView.style.top = cursorTop + 'px';
+      this.compositionView.style.height = cursor.offsetHeight + 'px';
+      this.compositionView.style.lineHeight = cursor.offsetHeight + 'px';
+      // Sync the textarea to the exact position of the composition view so the IME knows where the
+      // text is.
+      var compositionViewBounds = this.compositionView.getBoundingClientRect();
+      this.textarea.style.left = cursor.offsetLeft + 'px';
+      this.textarea.style.top = cursorTop + 'px';
+      this.textarea.style.width = compositionViewBounds.width + 'px';
+      this.textarea.style.height = compositionViewBounds.height + 'px';
+      this.textarea.style.lineHeight = compositionViewBounds.height + 'px';
+    }
+    if (!dontRecurse) {
+      setTimeout(this.updateCompositionElements.bind(this, true), 0);
+    }
+  };
 
-    this.compositionView.style.left = cursor.offsetLeft + 'px';
-    this.compositionView.style.top = cursorTop + 'px';
-    this.compositionView.style.height = cursor.offsetHeight + 'px';
-    this.compositionView.style.lineHeight = cursor.offsetHeight + 'px';
-    // Sync the textarea to the exact position of the composition view so the IME knows where the
-    // text is.
-    var compositionViewBounds = this.compositionView.getBoundingClientRect();
-    this.textarea.style.left = cursor.offsetLeft + 'px';
-    this.textarea.style.top = cursorTop + 'px';
-    this.textarea.style.width = compositionViewBounds.width + 'px';
-    this.textarea.style.height = compositionViewBounds.height + 'px';
-    this.textarea.style.lineHeight = compositionViewBounds.height + 'px';
-  }
-  if (!dontRecurse) {
-    setTimeout(this.updateCompositionElements.bind(this, true), 0);
-  }
-};
-
-/**
- * Clears the textarea's position so that the cursor does not blink on IE.
- * @private
- */
-CompositionHelper.prototype.clearTextareaPosition = function() {
-  this.textarea.style.left = '';
-  this.textarea.style.top = '';
-};
-
-export { CompositionHelper };
+  /**
+   * Clears the textarea's position so that the cursor does not blink on IE.
+   * @private
+   */
+  private clearTextareaPosition() {
+    this.textarea.style.left = '';
+    this.textarea.style.top = '';
+  };
+}
diff --git a/src/Interfaces.ts b/src/Interfaces.ts
index 14355e57..55cceb8b 100644
--- a/src/Interfaces.ts
+++ b/src/Interfaces.ts
@@ -4,11 +4,17 @@
  */
 
 export interface ITerminal {
+  element: HTMLElement;
   rowContainer: HTMLElement;
   ydisp: number;
   lines: string[];
   rows: number;
 
+  /**
+   * Emit the 'data' event and populate the given data.
+   * @param data The data to populate in the event.
+   */
+  handler(data: string);
   on(event: string, callback: () => void);
   scrollDisp(disp: number, suppressScrollEvent: boolean);
 }
diff --git a/src/xterm.js b/src/xterm.js
index c88423d4..0ef9427d 100644
--- a/src/xterm.js
+++ b/src/xterm.js
@@ -5129,7 +5129,6 @@ var wcwidth = (function(opts) {
  */
 
 Terminal.EventEmitter = EventEmitter;
-Terminal.CompositionHelper = CompositionHelper;
 Terminal.Viewport = Viewport;
 Terminal.inherits = inherits;