diff --git a/.gitignore b/.gitignore
index 10d09b5..c5a0c24 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,3 +3,4 @@ npm-debug.log
 .idea
 test/domassist.test.dist.js
 dist
+*js.map
diff --git a/lib/idStorage.js b/lib/idStorage.js
new file mode 100644
index 0000000..23f3106
--- /dev/null
+++ b/lib/idStorage.js
@@ -0,0 +1,61 @@
+const storage = new Map();
+
+const idStorage = {
+  areSimilar(a, b) {
+    const everyKey = f => Object.keys(a).every(f);
+    const type = ({}).toString
+      .call(a)
+      .match(/\[object (\w+)\]/)[1];
+
+    switch (type) {
+      case 'Array':
+        return a.length === b.length &&
+          everyKey(k => idStorage.areSimilar(a.sort()[k], b.sort()[k]));
+      case 'Object':
+        return Object.keys(a).length === Object.keys(b).length &&
+          everyKey(k => idStorage.areSimilar(a[k], b[k]));
+      default:
+        return a === b;
+    }
+  },
+
+  add(data) {
+    const id = idStorage.generateID();
+    storage.set(id, data);
+
+    return id;
+  },
+
+  generateID() {
+    const h = n => (n | 0).toString(16);
+    const s = n => h((Math.random() * (1 << (n << 2))) ^ Date.now()).slice(-n);
+
+    return [
+      s(4) + s(4), s(4),
+      `4${s(3)}`,
+      h(8 | (Math.random() * 4)) + s(3),
+      Date.now().toString(16).slice(-10) + s(2)
+    ].join('-');
+  },
+
+  removeFromID(id) {
+    const val = storage.get(id);
+    storage.delete(id);
+
+    return val;
+  },
+
+  removeFromValue(value) {
+    let found = null;
+
+    storage.forEach((val, key) => {
+      if (!found && idStorage.areSimilar(val, value)) {
+        found = key;
+      }
+    });
+
+    return idStorage.removeFromID(found);
+  }
+};
+
+export default idStorage;
diff --git a/lib/modify.js b/lib/modify.js
index 2a89fc7..48e48a2 100644
--- a/lib/modify.js
+++ b/lib/modify.js
@@ -6,9 +6,7 @@ import on from './on';
 import styles from './styles';
 
 function bindEvents(el, events) {
-  Object.keys(events).forEach((event) => {
-    on(el, event, events[event]);
-  });
+  return Object.keys(events).map(event => on(el, event, events[event]));
 }
 
 function modify(selector, params) {
@@ -25,11 +23,12 @@ function modify(selector, params) {
   const els = find(selector);
   if (els.length) {
     els.forEach((el) => {
-      Object.keys(params).forEach((param, index) => {
+      Object.keys(params).forEach(param => {
         if (param in modules) {
           if (param === 'events') {
-            bindEvents(el, params[param]);
+            return bindEvents(el, params[param]);
           }
+
           modules[param](el, params[param]);
         }
       });
diff --git a/lib/off.js b/lib/off.js
index a859db8..980fafd 100644
--- a/lib/off.js
+++ b/lib/off.js
@@ -1,22 +1,33 @@
 import find from './find';
+import idStorage from './idStorage';
 
-function off(selector, event) {
+function off(selector, event, handler, capture = false) {
   if (Array.isArray(selector)) {
-    selector.forEach((item) => off(item, event));
-  }
-  if (!window._domassistevents) {
-    window._domassistevents = {};
+    selector.forEach((item) => off(item, event, handler, capture));
   }
 
-  const data = window._domassistevents[`_${event}`];
+  // ID
+  if (typeof selector === 'string' && typeof event === 'undefined') {
+    const data = idStorage.removeFromID(selector);
+
+    if (!data) {
+      return;
+    }
 
-  if (!data) {
-    return;
+    return off(data.el, data.event, data.handler, data.capture);
   }
+
   const el = find(selector);
+
   if (el.length) {
     el.forEach((item) => {
-      item.removeEventListener(event, data.cb, data.capture);
+      item.removeEventListener(event, handler);
+      idStorage.removeFromValue({
+        el: item,
+        event,
+        handler,
+        capture
+      });
     });
   }
 }
diff --git a/lib/on.js b/lib/on.js
index 713ade5..a83dc77 100644
--- a/lib/on.js
+++ b/lib/on.js
@@ -1,27 +1,33 @@
 import find from './find';
+import idStorage from './idStorage';
 
-function on(selector, event, cb, capture = false) {
+function on(selector, event, handler, capture = false) {
   if (Array.isArray(selector)) {
-    selector.forEach((item) => on(item, event, cb, capture));
-    return;
+    return Array.prototype.concat.apply([],
+      selector.map(item => on(item, event, handler, capture)));
   }
 
-  const data = {
-    cb,
-    capture
-  };
-
-  if (!window._domassistevents) {
-    window._domassistevents = {};
-  }
-
-  window._domassistevents[`_${event}`] = data;
   const el = find(selector);
+  let ids = null;
+
   if (el.length) {
-    el.forEach((item) => {
-      item.addEventListener(event, cb, capture);
+    ids = el.map(item => {
+      item.addEventListener(event, handler);
+
+      return idStorage.add({
+        el: item,
+        event,
+        handler,
+        capture
+      });
     });
+
+    if (ids.length === 1) {
+      ids = ids[0];
+    }
   }
+
+  return ids;
 }
 
 export default on;
diff --git a/lib/once.js b/lib/once.js
index 6582f68..5069cbd 100644
--- a/lib/once.js
+++ b/lib/once.js
@@ -1,10 +1,24 @@
 import on from './on';
 import off from './off';
+import find from './find';
 
-function once(el, event, run, capture = false) {
-  on(el, event, e => {
-    off(el, event);
-    run(e);
+function once(selector, event, handler, capture = false) {
+  if (Array.isArray(selector)) {
+    selector.forEach(item => once(item, event, handler, capture));
+    return;
+  }
+
+  const el = find(selector);
+
+  if (el.length > 1) {
+    // Need to get the event id for each element so once runs properly
+    once(el, event, handler, capture);
+    return;
+  }
+
+  const eventId = on(el, event, e => {
+    off(eventId);
+    handler(e);
   }, capture);
 }
 
diff --git a/package.json b/package.json
index 7686366..2f51348 100644
--- a/package.json
+++ b/package.json
@@ -29,6 +29,7 @@
   "devDependencies": {
     "eslint-config-firstandthird": "3.2.0",
     "eslint-plugin-import": "^2.1.0",
+    "map-polyfill": "0.0.1",
     "phantomjs-prebuilt": "^2.1.14",
     "scriptkit": "0.2.0",
     "static-server": "^2.0.3",
diff --git a/test/domassist.test.js b/test/domassist.test.js
index 1c372dc..7fef05c 100644
--- a/test/domassist.test.js
+++ b/test/domassist.test.js
@@ -1,5 +1,6 @@
 /* eslint no-console: 0 */
 
+import '../node_modules/map-polyfill/dist/map.min';
 import domassist from '../domassist';
 import test from 'tape-rollup';
 import { teardown } from './setup';
@@ -14,8 +15,7 @@ import './modify.test';
 import './show-hide.test';
 import './styles.test';
 import './append.test';
-
-const page = window.phantom.page;
+import TestUtils from './test-utils';
 
 test('ready', assert => {
   // if you add more assertions update this number
@@ -117,9 +117,7 @@ test('Events - delegate', assert => {
   `;
 
   const button = domassist.findOne('button', el);
-  const pos = button.getBoundingClientRect();
-
-  page.sendEvent('click', pos.left + pos.width / 2, pos.top + pos.height / 2);
+  button.click();
 });
 
 test('Events - once', assert => {
@@ -130,17 +128,15 @@ test('Events - once', assert => {
   `;
 
   const link = domassist.findOne('a', el);
-  const pos = link.getBoundingClientRect();
 
   let clicks = 0;
-
   domassist.once(link, 'click', e => {
     clicks++;
   });
 
-  page.sendEvent('click', pos.left + pos.width / 2, pos.top + pos.height / 2);
-  page.sendEvent('click', pos.left + pos.width / 2, pos.top + pos.height / 2);
-  page.sendEvent('click', pos.left + pos.width / 2, pos.top + pos.height / 2);
+  link.click();
+  link.click();
+  link.click();
 
   setTimeout(() => {
     assert.equal(clicks, 1, 'Only fired once');
@@ -152,21 +148,21 @@ test('Events - hover', assert => {
   const el = domassist.findOne('#domassist');
 
   el.innerHTML = `
-    <div style="height: 100px; width: 100px;"></div>
+    <div></div>
   `;
 
   const box = domassist.findOne('div', el);
-  const pos = box.getBoundingClientRect();
 
   domassist.hover(box, e => {
-    assert.ok(e instanceof MouseEvent, 'Enter fired');
+    assert.pass('Enter fired');
     assert.equal(e.type, 'mouseenter', 'Correct event');
   }, e => {
-    assert.ok(e instanceof MouseEvent, 'Leave fired');
+    assert.pass('Leave fired');
     assert.equal(e.type, 'mouseleave', 'Correct event');
-    assert.end();
   });
 
-  page.sendEvent('mousemove', pos.left + pos.width / 2, pos.top + pos.height / 2);
-  page.sendEvent('mousemove', pos.left + pos.width + 100, pos.top + pos.height + 100);
+  TestUtils.fireEvent(box, 'mouseenter');
+  TestUtils.fireEvent(box, 'mouseleave');
+
+  assert.end();
 });
diff --git a/test/index.html b/test/index.html
new file mode 100644
index 0000000..cb44594
--- /dev/null
+++ b/test/index.html
@@ -0,0 +1,13 @@
+<!doctype html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8">
+  <meta name="viewport"
+        content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
+  <meta http-equiv="X-UA-Compatible" content="ie=edge">
+  <title>Document</title>
+</head>
+<body>
+  <script src="domassist.test.dist.js"></script>
+</body>
+</html>
diff --git a/test/modify.test.js b/test/modify.test.js
index 2061ffa..9c75777 100644
--- a/test/modify.test.js
+++ b/test/modify.test.js
@@ -1,5 +1,6 @@
 import domassist from '../domassist';
 import test from 'tape-rollup';
+import TestUtils from './test-utils';
 
 const setup = (total) => {
   const frag = document.createDocumentFragment();
@@ -21,8 +22,6 @@ const teardown = (el) => {
   }
 };
 
-const page = window.phantom.page;
-
 test('modify - add class', assert => {
   const el = domassist.findOne('#domassist');
   domassist.modify(el, {
@@ -71,33 +70,31 @@ test('modify - html', assert => {
 });
 //
 test('modify - events', assert => {
-  // assert.plan(5);
   const el = domassist.findOne('#domassist');
   el.innerHTML = `
     <a style="display: block; height: 100px; width: 100px;" href="#">Click</a>
   `;
   const link = domassist.findOne('a');
-  const pos = link.getBoundingClientRect();
   domassist.modify(link, {
     events: {
       click: (e) => {
-        assert.ok(e instanceof MouseEvent, 'Click event fired');
+        assert.pass('Click fired');
       },
       mouseenter: (e) => {
-        assert.ok(e instanceof MouseEvent, 'Enter fired');
+        assert.pass('Enter fired');
         assert.equal(e.type, 'mouseenter', 'Correct event');
       },
       mouseleave: (e) => {
-        assert.ok(e instanceof MouseEvent, 'Leave fired');
+        assert.pass('Leave fired');
         assert.equal(e.type, 'mouseleave', 'Correct event');
-        assert.end();
       }
     }
   });
 
-  page.sendEvent('click', pos.left + pos.width / 2, pos.top + pos.height / 2);
-  page.sendEvent('mousemove', pos.left + pos.width / 2, pos.top + pos.height / 2);
-  page.sendEvent('mousemove', pos.left + pos.width + 100, pos.top + pos.height + 100);
+  link.click();
+  TestUtils.fireEvent(link, 'mouseenter');
+  TestUtils.fireEvent(link, 'mouseleave');
+  assert.end();
 });
 test('modify - styles', assert => {
   const el = domassist.findOne('#domassist');
diff --git a/test/off.test.js b/test/off.test.js
index 87a8b9d..9fef0cb 100644
--- a/test/off.test.js
+++ b/test/off.test.js
@@ -1,36 +1,73 @@
 import domassist from '../domassist';
 import test from 'tape-rollup';
 
-const page = window.phantom.page;
-
-test('Events - off single element', assert => {
+test('Events - off single element single event', assert => {
   const el = domassist.findOne('#domassist');
-  assert.plan(1);
   el.innerHTML = `
     <a href="#">Click</a>
   `;
 
   const link = domassist.findOne('a', el);
-  const pos = link.getBoundingClientRect();
+  const handler = () => {
+    assert.fail('I should not fire');
+  };
+
+  domassist.on(link, 'click', handler);
+  domassist.off(link, 'click', handler);
+
+  link.click();
+
+  assert.ok('No events fired');
+  assert.end();
+});
+
+test('Events - off multiple elements', assert => {
+  const el = domassist.findOne('#domassist');
+  el.innerHTML = `
+    <a data-id="link-1" href="#">Click</a>
+    <a data-id="link-2" href="#">Click</a>
+    <a data-id="link-3" href="#">Click</a>
+    <a data-id="link-4" href="#">Click</a>
+  `;
+
+  const links = domassist.find('a', el);
+  const handler = () => {
+    assert.fail('I should never fire');
+  };
 
-  let clicked = false;
+  domassist.on(links, 'click', handler);
+  domassist.off(links, 'click', handler);
 
-  domassist.on(link, 'click', e => {
-    clicked = true;
+  links.forEach(item => {
+    item.click();
   });
 
-  domassist.off(link, 'click');
+  assert.ok('No events fired');
+  assert.end();
+});
+
+test('Events - off with id', assert => {
+  const el = domassist.findOne('#domassist');
+  el.innerHTML = `
+    <a href="#">Click</a>
+  `;
+
+  const link = domassist.findOne('a', el);
+  const handler = () => {
+    assert.fail('I should not fire');
+  };
 
-  page.sendEvent('click', pos.left + pos.width / 2, pos.top + pos.height / 2);
+  const id = domassist.on(link, 'click', handler);
+  domassist.off(id);
 
-  setTimeout(() => {
-    assert.ok(!clicked, 'Event not fired');
-  }, 500);
+  link.click();
+
+  assert.ok('No events fired');
+  assert.end();
 });
 
-test('Events - off multiple elements', assert => {
+test('Events - off with array of ids', assert => {
   const el = domassist.findOne('#domassist');
-  assert.plan(4);
   el.innerHTML = `
     <a data-id="link-1" href="#">Click</a>
     <a data-id="link-2" href="#">Click</a>
@@ -39,20 +76,20 @@ test('Events - off multiple elements', assert => {
   `;
 
   const links = domassist.find('a', el);
-  domassist.on(links, 'click', e => {
-    const id = parseInt(e.target.dataset.id.replace('link-', ''), 10);
-    const div = document.createElement('div');
-    div.id = `id-${id}`;
-    el.appendChild(div);
-  });
-  // domassist.off(links, 'click');
-  links.forEach((item, index) => {
-    const pos = item.getBoundingClientRect();
-    const id = `id-${index + 1}`;
-    page.sendEvent('click', pos.left + pos.width / 2, pos.top + pos.height / 2);
-    const div = domassist.findOne(`#${id}`);
-    setTimeout(() => {
-      assert.equal(div.id, id, `Element with ID link-${index + 1} has no click event`);
-    }, 500);
+  const handler = () => {
+    assert.fail('I should never fire');
+  };
+
+  const ids = domassist.on(links, 'click', handler);
+
+  assert.ok(Array.isArray(ids), 'Ids should be an array');
+  assert.equal(ids.length, 4, 'Should have 4 ids');
+
+  domassist.off(ids);
+  links.forEach(item => {
+    item.click();
   });
+
+  assert.ok('No events fired');
+  assert.end();
 });
diff --git a/test/on.test.js b/test/on.test.js
index a38d0fd..80f6be5 100644
--- a/test/on.test.js
+++ b/test/on.test.js
@@ -1,8 +1,6 @@
 import domassist from '../domassist';
 import test from 'tape-rollup';
 
-const page = window.phantom.page;
-
 test('Events - on single element', assert => {
   const el = domassist.findOne('#domassist');
   assert.plan(1);
@@ -10,13 +8,12 @@ test('Events - on single element', assert => {
     <a href="#">Click</a>
   `;
   const link = domassist.findOne('a');
-  const pos = link.getBoundingClientRect();
 
   domassist.on(link, 'click', e => {
     assert.ok(e instanceof MouseEvent, 'Event fired');
   });
 
-  page.sendEvent('click', pos.left + pos.width / 2, pos.top + pos.height / 2);
+  link.click();
 });
 
 test('Events - on multiple elements', assert => {
@@ -34,8 +31,7 @@ test('Events - on multiple elements', assert => {
     assert.equal(e.target.id, `link-${index}`, `Link with id of link-${index} fired`);
   });
   links.forEach((item) => {
-    const pos = item.getBoundingClientRect();
-    page.sendEvent('click', pos.left + pos.width / 2, pos.top + pos.height / 2);
+    item.click();
     index += 1;
   });
 });
diff --git a/test/test-utils.js b/test/test-utils.js
new file mode 100644
index 0000000..18957f4
--- /dev/null
+++ b/test/test-utils.js
@@ -0,0 +1,8 @@
+export default {
+  fireEvent(el, type) {
+    const evt = document.createEvent('CustomEvent');
+    evt.initCustomEvent(type, false, false, null);
+
+    el.dispatchEvent(evt);
+  }
+};