diff --git a/architype.js b/architype.js
index cb01d0a..9a163eb 100644
--- a/architype.js
+++ b/architype.js
@@ -1,132 +1,178 @@
-let def = document.getElementById('definition');
+'use strict';
 
-document.addEventListener('keydown', e => {
-  console.log(e.key);
-
-  let sel = def.getElementsByClassName('selected').item(0);
-
-  switch (e.key) {
-    case 'd':
-      if (sel) {
-        let newSel = sel.nextElementSibling || sel.previousElementSibling;
-        if (newSel) {
-          newSel.classList.add('selected');
-        }
-        sel.remove();
-      }
-      break;
-
-    case 'D':
-      while (sel.nextElementSibling) {
-        sel.nextElementSibling.remove();
-      }
-      if (sel.previousElementSibling) {
-        sel.previousElementSiblist.classList.add('selected');
-      }
-      sel.remove();
-      break;
-
-    case 'j':
-    case 'ArrowDown':
-      if (sel) {
-        let newSel = sel.nextElementSibling || def.firstElementChild;
-        sel.classList.remove('selected');
-        newSel.classList.add('selected');
-      }
-      break;
-
-    case 'k':
-    case 'ArrowUp':
-      if (sel) {
-        let newSel = sel.previousElementSibling || def.lastElementChild;
-        sel.classList.remove('selected');
-        newSel.classList.add('selected');
-      }
-      break;
-
-    case 'PageUp':
-      if (sel) {
-        let pageCount = Math.floor(def.clientHeight / sel.clientHeight) - 1;
-        let newSel = sel;
-        for (let i = 0; i < pageCount; ++i) {
-          newSel = newSel.previousElementSibling || def.firstElementChild;
-        }
-        sel.classList.remove('selected');
-        newSel.classList.add('selected');
-      }
-      break;
-
-    case 'PageDown':
-      if (sel) {
-        let pageCount = Math.floor(def.clientHeight / sel.clientHeight) - 1;
-        let newSel = sel;
-        for (let i = 0; i < pageCount; ++i) {
-          newSel = newSel.nextElementSibling || def.lastElementChild;
-        }
-        sel.classList.remove('selected');
-        newSel.classList.add('selected');
-      }
-      break;
-
-    case 'Home':
-      if (sel) {
-        sel.classList.remove('selected');
-        def.firstElementChild.classList.add('selected');
-      }
-      break;
-
-    case 'G': // vi compat
-    case 'End':
-      if (sel) {
-        sel.classList.remove('selected');
-        def.lastElementChild.classList.add('selected');
-      }
-      break;
-
-    case 'n':
-      {
-        let node = document.createElement('li');
-        node.innerText = 'Node: ';
-
-        let input = document.createElement('input');
-        input.type = 'text';
-        node.appendChild(input);
-
-        node.classList.add('node');
-        def.insertBefore(node, sel ? sel.nextSibling : null);
-
-        if (sel) {
-          sel.classList.remove('selected');
-        }
-        node.classList.add('selected');
-      }
-      break;
-
-    case 'N':
-      {
-        let node = document.createElement('li');
-        node.innerText = 'Node: ';
-
-        let input = document.createElement('input');
-        input.type = 'text';
-        node.appendChild(input);
-
-        node.classList.add('node');
-        def.insertBefore(node, sel);
-
-        if (sel) {
-          sel.classList.remove('selected');
-        }
-        node.classList.add('selected');
-      }
-      break;
+class Editor {
+  constructor(container) {
+    this.container_ = container;
   }
 
-  sel = def.getElementsByClassName('selected').item(0);
+  getSelected() {
+    return this.container_.getElementsByClassName('selected').item(0);
+  }
 
-  if (sel) {
-    sel.scrollIntoView({
+  deleteSelected() {
+    let sel = this.getSelected();
+    let newSel = sel.nextElementSibling || sel.previousElementSibling;
+    sel.remove();
+    this.select(newSel);
+  }
+
+  deleteSelectedAndAfter() {
+    let sel = this.getSelected();
+    while (sel.nextElementSibling) {
+      sel.nextElementSibling.remove();
+    }
+    let newSel = null;
+    if (sel.previousElementSibling) {
+      newSel = sel.previousElementSibling;
+    }
+    sel.remove();
+    this.select(newSel);
+  }
+
+  selectNext() {
+    this.select(this.getSelected().nextElementSibling ||
+                this.container_.firstElementChild);
+  }
+
+  selectPrev() {
+    this.select(this.getSelected().previousElementSibling ||
+                this.container_.lastElementChild);
+  }
+
+  selectPrevPage() {
+    let targetTop = this.container_.scrollTop - this.container_.clientHeight;
+    let newSel = this.getSelected();
+    while (newSel.previousElementSibling &&
+           this.container_.scrollTop > targetTop) {
+      newSel = newSel.previousElementSibling;
+      this.select(newSel);
+    }
+  }
+
+  selectNextPage() {
+    let targetTop = this.container_.scrollTop + this.container_.clientHeight;
+    let newSel = this.getSelected();
+    while (newSel.nextElementSibling && this.container_.scrollTop < targetTop) {
+      newSel = newSel.nextElementSibling;
+      this.select(newSel);
+    }
+  }
+
+  selectFirst() {
+    this.select(this.container_.firstElementChild);
+  }
+
+  selectLast() {
+    this.select(this.container_.lastElementChild);
+  }
+
+  select(elem) {
+    if (!elem) {
+      return;
+    }
+    let sel = this.getSelected();
+    if (sel) {
+      sel.classList.remove('selected');
+    }
+    elem.classList.add('selected');
+    elem.scrollIntoView({
       block: 'center',
     });
   }
-});
+
+  addNodeAfter() {
+    let node = Node.addAfter(this.container_, this.getSelected());
+    this.select(node);
+  }
+
+  addNodeBefore() {
+    let node = Node.addBefore(this.container_, this.getSelected());
+    this.select(node);
+  }
+
+  onKeyDown(e) {
+    // Keys that work with an empty list
+    switch (e.key) {
+      case 'n':
+        this.addNodeAfter();
+        break;
+
+      case 'N':
+        this.addNodeBefore();
+        break;
+    }
+
+    if (!this.container_.firstElementChild) {
+      return;
+    }
+
+    // Keys that require a current selection
+    switch (e.key) {
+      case 'd':
+        this.deleteSelected();
+        break;
+
+      case 'D':
+        this.deleteSelectedAndAfter();
+        break;
+
+      case 'j':
+      case 'ArrowDown':
+        this.selectNext();
+        break;
+
+      case 'k':
+      case 'ArrowUp':
+        this.selectPrev();
+        break;
+
+      case 'PageUp':
+        this.selectPrevPage();
+        break;
+
+      case 'PageDown':
+        this.selectNextPage();
+        break;
+
+      case 'Home':
+        this.selectFirst();
+        break;
+
+      case 'G': // vi compat
+      case 'End':
+        this.selectLast();
+        break;
+    }
+  }
+}
+
+class Node {
+  constructor() {
+    this.elem_ = document.createElement('li');
+    this.elem_.innerText = 'Node: ';
+
+    let input = document.createElement('input');
+    input.type = 'text';
+    this.elem_.appendChild(input);
+
+    this.elem_.classList.add('node');
+
+    // TODO: fix reference loop
+    this.elem_.xArchObj = this;
+  }
+
+  static addBefore(container, elem) {
+    let node = new Node();
+    container.insertBefore(node.elem_, elem);
+    return node.elem_;
+  }
+
+  static addAfter(container, elem) {
+    let node = new Node();
+    container.insertBefore(node.elem_, elem ? elem.nextSibling : null);
+    return node.elem_;
+  }
+}
+
+let editor = new Editor(document.getElementById('definition'));
+document.addEventListener('keydown', e => { editor.onKeyDown(e); });