diff --git a/spec/regexper_spec.js b/spec/regexper_spec.js
index 34835db..42629a7 100644
--- a/spec/regexper_spec.js
+++ b/spec/regexper_spec.js
@@ -96,6 +96,41 @@ describe('regexper.js', function() {
 
   });
 
+  describe('#documentKeypressListener', function() {
+
+    beforeEach(function() {
+      this.event = document.createEvent('Event');
+      spyOn(parser, 'cancel');
+    });
+
+    describe('when the keyCode is not 27 (Escape)', function() {
+
+      beforeEach(function() {
+        this.event.keyCode = 42;
+      });
+
+      it('does not cancel the parser', function() {
+        this.regexper.documentKeypressListener(this.event);
+        expect(parser.cancel).not.toHaveBeenCalled();
+      });
+
+    });
+
+    describe('when the keyCode is 27 (Escape)', function() {
+
+      beforeEach(function() {
+        this.event.keyCode = 27;
+      });
+
+      it('cancels the parser', function() {
+        this.regexper.documentKeypressListener(this.event);
+        expect(parser.cancel).toHaveBeenCalled();
+      });
+
+    });
+
+  });
+
   describe('#submitListener', function() {
 
     beforeEach(function() {
@@ -168,9 +203,16 @@ describe('regexper.js', function() {
 
   describe('#bindListeners', function() {
 
+    beforeEach(function() {
+      spyOn(this.regexper, 'keypressListener');
+      spyOn(this.regexper, 'submitListener');
+      spyOn(this.regexper, 'updatePercentage');
+      spyOn(this.regexper, 'documentKeypressListener');
+      spyOn(this.regexper, 'hashchangeListener');
+    });
+
     it('binds #keypressListener to keypress on the text field', function() {
       spyOn(this.regexper.field, 'addEventListener');
-      spyOn(this.regexper, 'keypressListener');
       this.regexper.bindListeners();
       expect(this.regexper.field.addEventListener).toHaveBeenCalledWith('keypress', jasmine.any(Function));
 
@@ -180,7 +222,6 @@ describe('regexper.js', function() {
 
     it('binds #submitListener to submit on the form', function() {
       spyOn(this.regexper.form, 'addEventListener');
-      spyOn(this.regexper, 'submitListener');
       this.regexper.bindListeners();
       expect(this.regexper.form.addEventListener).toHaveBeenCalledWith('submit', jasmine.any(Function));
 
@@ -190,17 +231,24 @@ describe('regexper.js', function() {
 
     it('binds #updatePercentage to updateStatus on the root', function() {
       spyOn(this.regexper.root, 'addEventListener');
-      spyOn(this.regexper, 'updatePercentage');
       this.regexper.bindListeners();
       expect(this.regexper.root.addEventListener).toHaveBeenCalledWith('updateStatus', jasmine.any(Function));
 
-      this.regexper.root.addEventListener.calls.mostRecent().args[1]();
+      this.regexper.root.addEventListener.calls.first().args[1]();
       expect(this.regexper.updatePercentage).toHaveBeenCalled();
     });
 
+    it('binds #documentKeypressListener to keyup on the root', function() {
+      spyOn(this.regexper.root, 'addEventListener');
+      this.regexper.bindListeners();
+      expect(this.regexper.root.addEventListener).toHaveBeenCalledWith('keyup', jasmine.any(Function));
+
+      this.regexper.root.addEventListener.calls.mostRecent().args[1]();
+      expect(this.regexper.documentKeypressListener).toHaveBeenCalled();
+    });
+
     it('binds #hashchangeListener to hashchange on the window', function() {
       spyOn(window, 'addEventListener');
-      spyOn(this.regexper, 'hashchangeListener');
       this.regexper.bindListeners();
       expect(window.addEventListener).toHaveBeenCalledWith('hashchange', jasmine.any(Function));
 
@@ -262,6 +310,21 @@ describe('regexper.js', function() {
 
       });
 
+      describe('when the parser is cancelled', function() {
+
+        beforeEach(function(done) {
+          spyOn(this.regexper, 'updateLinks');
+          this.regexper.showExpression('example expression');
+          this.renderPromise.reject('Render cancelled');
+          setTimeout(done, 100);
+        });
+
+        it('clears the state', function() {
+          expect(this.regexper.state).toEqual('');
+        });
+
+      });
+
     });
 
   });
diff --git a/src/js/parser/javascript.js b/src/js/parser/javascript.js
index 2713f8b..f7e1f9a 100644
--- a/src/js/parser/javascript.js
+++ b/src/js/parser/javascript.js
@@ -41,8 +41,14 @@ parser.Parser.RepeatSpec      = { module: RepeatSpec };
 parser.parse = (parse => {
   return function() {
     Subexp.resetCounter();
+    Node.reset();
+
     return parse.apply(this, arguments);
   };
 })(parser.parse);
 
+parser.cancel = () => {
+  Node.cancelRender = true;
+};
+
 export default parser;
diff --git a/src/js/parser/javascript/node.js b/src/js/parser/javascript/node.js
index b7a0892..dadd8b1 100644
--- a/src/js/parser/javascript/node.js
+++ b/src/js/parser/javascript/node.js
@@ -1,9 +1,6 @@
 import _ from 'lodash';
 import Q from 'q';
 
-var renderCounter = 0,
-    maxCounter = 0;
-
 export default class Node {
   constructor(textValue, offset, elements, properties) {
     this.textValue = textValue;
@@ -66,57 +63,69 @@ export default class Node {
     return this.container.transform(matrix);
   }
 
-  renderLabel(text) {
+  deferredStep() {
     var deferred = Q.defer(),
-        group = this.container.group()
+        result = arguments;
+
+    setTimeout(() => {
+      if (Node.cancelRender) {
+        deferred.reject('Render cancelled');
+      } else {
+        deferred.resolve.apply(this, result);
+      }
+    }, 1);
+
+    return deferred.promise;
+  }
+
+  renderLabel(text) {
+    var group = this.container.group()
           .addClass('label'),
         rect = group.rect(),
         text = group.text(0, 0, _.flatten([text]));
 
-    setTimeout(deferred.resolve.bind(deferred, group));
-    deferred.promise.then(() => {
-      var box = text.getBBox(),
-          margin = 5;
+    return this.deferredStep(group)
+      .then(group => {
+        var box = text.getBBox(),
+            margin = 5;
 
-      text.transform(Snap.matrix()
-        .translate(margin, box.height / 2 + 2 * margin));
+        text.transform(Snap.matrix()
+          .translate(margin, box.height / 2 + 2 * margin));
 
-      rect.attr({
-        width: box.width + 2 * margin,
-        height: box.height + 2 * margin
+        rect.attr({
+          width: box.width + 2 * margin,
+          height: box.height + 2 * margin
+        });
+
+        return group;
       });
-    });
-
-    return deferred.promise;
   }
 
   startRender() {
-    renderCounter++;
+    Node.renderCounter++;
   }
 
   doneRender() {
-    var evt, deferred = Q.defer();
+    var evt;
 
-    if (maxCounter === 0) {
-      maxCounter = renderCounter;
+    if (Node.maxCounter === 0) {
+      Node.maxCounter = Node.renderCounter;
     }
 
-    renderCounter--;
+    Node.renderCounter--;
 
     evt = document.createEvent('Event');
     evt.initEvent('updateStatus', true, true);
     evt.detail = {
-      percentage: (maxCounter - renderCounter) / maxCounter
+      percentage: (Node.maxCounter - Node.renderCounter) / Node.maxCounter
     };
     document.body.dispatchEvent(evt);
 
-    if (renderCounter === 0) {
-      maxCounter = 0;
+    if (Node.renderCounter === 0) {
+      Node.maxCounter = 0;
     }
 
-    setTimeout(deferred.resolve.bind(deferred), 1);
-
-    return deferred.promise;
+    return this.deferredStep();
   }
 
   render(container) {
@@ -191,8 +200,7 @@ export default class Node {
   }
 
   renderLabeledBox(label, content, options) {
-    var deferred = Q.defer(),
-        label = this.container.text()
+    var label = this.container.text()
           .addClass([this.type, 'label'].join('-'))
           .attr({
             text: label
@@ -211,26 +219,30 @@ export default class Node {
     this.container.prepend(label);
     this.container.prepend(box);
 
-    setTimeout(deferred.resolve);
-    deferred.promise.then(() => {
-      var labelBox = label.getBBox(),
-          contentBox = content.getBBox();
+    return this.deferredStep()
+      .then(() => {
+        var labelBox = label.getBBox(),
+            contentBox = content.getBBox();
 
-      label.transform(Snap.matrix()
-        .translate(0, labelBox.height));
+        label.transform(Snap.matrix()
+          .translate(0, labelBox.height));
 
-      box
-        .transform(Snap.matrix()
-          .translate(0, labelBox.height))
-        .attr({
-          width: Math.max(contentBox.width + options.padding * 2, labelBox.width),
-          height: contentBox.height + options.padding * 2
-        });
+        box
+          .transform(Snap.matrix()
+            .translate(0, labelBox.height))
+          .attr({
+            width: Math.max(contentBox.width + options.padding * 2, labelBox.width),
+            height: contentBox.height + options.padding * 2
+          });
 
-      content.transform(Snap.matrix()
-        .translate(box.getBBox().cx - contentBox.cx, labelBox.height + options.padding));
-    });
-
-    return deferred.promise;
+        content.transform(Snap.matrix()
+          .translate(box.getBBox().cx - contentBox.cx, labelBox.height + options.padding));
+      });
   }
 };
+
+Node.reset = () => {
+  Node.renderCounter = 0;
+  Node.maxCounter = 0;
+  Node.cancelRender = false;
+};
diff --git a/src/js/regexper.js b/src/js/regexper.js
index a6d98ba..70a7a1f 100644
--- a/src/js/regexper.js
+++ b/src/js/regexper.js
@@ -32,6 +32,12 @@ export default class Regexper {
     }
   }
 
+  documentKeypressListener(event) {
+    if (event.keyCode === 27) {
+      parser.cancel();
+    }
+  }
+
   submitListener(event) {
     event.returnValue = false;
     if (event.preventDefault) {
@@ -62,6 +68,7 @@ export default class Regexper {
     this.field.addEventListener('keypress', this.keypressListener.bind(this));
     this.form.addEventListener('submit', this.submitListener.bind(this));
     this.root.addEventListener('updateStatus', this.updatePercentage.bind(this));
+    this.root.addEventListener('keyup', this.documentKeypressListener.bind(this));
     window.addEventListener('hashchange', this.hashchangeListener.bind(this));
   }
 
@@ -92,6 +99,12 @@ export default class Regexper {
         .then(() => {
           this.state = 'has-results';
           this.updateLinks();
+        }, (message) => {
+          if (message === 'Render cancelled') {
+            this.state = '';
+          } else {
+            throw message;
+          }
         })
         .done();
     }