diff --git a/backup/fileSaveLoad.js b/backup/fileSaveLoad.js
index 0cfc22e3..57f69e30 100644
--- a/backup/fileSaveLoad.js
+++ b/backup/fileSaveLoad.js
@@ -1,9 +1,8 @@
 /* globals getStyles, saveStyle, invalidateCache, refreshAllTabs, handleUpdate */
 'use strict';
 
-var STYLISH_DUMP_FILE_EXT = '.txt';
-var STYLISH_DUMPFILE_EXTENSION = '.json';
-var STYLISH_DEFAULT_SAVE_NAME = 'stylus-mm-dd-yyyy' + STYLISH_DUMP_FILE_EXT;
+const STYLISH_DUMP_FILE_EXT = '.txt';
+const STYLUS_BACKUP_FILE_EXT = '.json';
 
 function importFromFile({fileTypeFilter, file} = {}) {
   return new Promise(resolve => {
@@ -47,52 +46,184 @@ function importFromFile({fileTypeFilter, file} = {}) {
 
 function importFromString(jsonString) {
   const json = runTryCatch(() => Array.from(JSON.parse(jsonString))) || [];
-  const numStyles = json.length;
+  const oldStyles = json.length && deepCopyStyles();
+  const oldStylesByName = json.length && new Map(
+    oldStyles.map(style => [style.name.trim(), style]));
+  const stats = {
+    added: {names: [], ids: [], legend: 'added'},
+    unchanged: {names: [], ids: [], legend: 'identical skipped'},
+    metaAndCode: {names: [], ids: [], legend: 'updated both meta info and code'},
+    metaOnly: {names: [], ids: [], legend: 'updated meta info'},
+    codeOnly: {names: [], ids: [], legend: 'updated code'},
+    invalid: {names: [], legend: 'invalid skipped'},
+  };
+  let index = 0;
+  return new Promise(proceed);
 
-  if (numStyles) {
-    invalidateCache(true);
+  function proceed(resolve) {
+    while (index < json.length) {
+      const item = json[index++];
+      if (!item || !item.name || !item.name.trim() || typeof item != 'object'
+      || (item.sections && !(item.sections instanceof Array))) {
+        stats.invalid.names.push(`#${index}: ${limitString(item && item.name || '')}`);
+        continue;
+      }
+      item.name = item.name.trim();
+      const byId = (cachedStyles.byId.get(item.id) || {}).style;
+      const byName = oldStylesByName.get(item.name);
+      const oldStyle = byId && byId.name.trim() == item.name || !byName ? byId : byName;
+      if (oldStyle == byName && byName) {
+        item.id = byName.id;
+      }
+      const oldStyleKeys = oldStyle && Object.keys(oldStyle);
+      const metaEqual = oldStyleKeys &&
+        oldStyleKeys.length == Object.keys(item).length &&
+        oldStyleKeys.every(k => k == 'sections' || oldStyle[k] === item[k]);
+      const codeEqual = oldStyle && styleSectionsEqual(oldStyle, item);
+      if (metaEqual && codeEqual) {
+        stats.unchanged.names.push(oldStyle.name);
+        stats.unchanged.ids.push(oldStyle.id);
+        continue;
+      }
+      saveStyle(item, {notify: false}).then(style => {
+        handleUpdate(style, {reason: 'import'});
+        setTimeout(proceed, 0, resolve);
+        if (!oldStyle) {
+          stats.added.names.push(style.name);
+          stats.added.ids.push(style.id);
+        }
+        else if (!metaEqual && !codeEqual) {
+          stats.metaAndCode.names.push(reportNameChange(oldStyle, style));
+          stats.metaAndCode.ids.push(style.id);
+        }
+        else if (!codeEqual) {
+          stats.codeOnly.names.push(style.name);
+          stats.codeOnly.ids.push(style.id);
+        }
+        else {
+          stats.metaOnly.names.push(reportNameChange(oldStyle, style));
+          stats.metaOnly.ids.push(style.id);
+        }
+      });
+      return;
+    }
+    done(resolve);
   }
 
-  return new Promise(resolve => {
-    proceed();
-    function proceed() {
-      const nextStyle = json.shift();
-      if (nextStyle) {
-        saveStyle(nextStyle, {notify: false}).then(style => {
-          handleUpdate(style, {reason: 'import'});
-          setTimeout(proceed, 0);
-        });
-      } else {
-        refreshAllTabs().then(() => {
-          scrollTo(0, 0);
-          setTimeout(alert, 100, numStyles + ' styles installed/updated');
-          resolve(numStyles);
-        });
+  function done(resolve) {
+    const numChanged = stats.metaAndCode.names.length +
+      stats.metaOnly.names.length +
+      stats.codeOnly.names.length +
+      stats.added.names.length;
+    Promise.resolve(numChanged && refreshAllTabs()).then(() => {
+      scrollTo(0, 0);
+      const report = Object.keys(stats)
+        .filter(kind => stats[kind].names.length)
+        .map(kind => `<details data-id="${kind}">
+            <summary><b>${stats[kind].names.length} ${stats[kind].legend}</b></summary>
+            <small>` + stats[kind].names.map((name, i) =>
+                `<div data-id="${stats[kind].ids[i]}">${name}</div>`).join('') + `
+            </small>
+          </details>`)
+        .join('');
+      const box = messageBox({
+        title: 'Finished importing styles',
+        contents: report || 'Nothing was changed.',
+        buttons: [t('confirmOK'), numChanged && t('undo')],
+        onclick: btnIndex => btnIndex == 1 && undo(),
+      });
+      bindClick(box);
+      resolve(numChanged);
+    });
+  }
+
+  function undo() {
+    const oldStylesById = new Map(oldStyles.map(style => [style.id, style]));
+    const newIds = [
+      ...stats.metaAndCode.ids,
+      ...stats.metaOnly.ids,
+      ...stats.codeOnly.ids,
+      ...stats.added.ids,
+    ];
+    index = 0;
+    return new Promise(undoNextId)
+      .then(refreshAllTabs)
+      .then(() => messageBox({
+        title: 'Import has been undone',
+        contents: newIds.length + ' styles were reverted.',
+        buttons: [t('confirmOK')],
+      }));
+    function undoNextId(resolve) {
+      if (index == newIds.length) {
+        resolve();
+        return;
+      }
+      const id = newIds[index++];
+      deleteStyle(id, {notify: false}).then(id => {
+        handleDelete(id);
+        const oldStyle = oldStylesById.get(id);
+        if (oldStyle) {
+          saveStyle(Object.assign(oldStyle, {reason: 'undoImport'}), {notify: false})
+            .then(handleUpdate)
+            .then(() => setTimeout(undoNextId, 0, resolve));
+        } else {
+          setTimeout(undoNextId, 0, resolve);
+        }
+      });
+    }
+  }
+
+  function bindClick(box) {
+    for (let block of [...box.querySelectorAll('details')]) {
+      if (block.dataset.id != 'invalid') {
+        block.style.cursor = 'pointer';
+        block.onclick = event => {
+          const styleElement = $(`[style-id="${event.target.dataset.id}"]`);
+          if (styleElement) {
+            scrollElementIntoView(styleElement);
+            highlightElement(styleElement);
+          }
+        };
       }
     }
-  });
-}
+  }
 
-function generateFileName() {
-  var today = new Date();
-  var dd = '0' + today.getDate();
-  var mm = '0' + (today.getMonth() + 1);
-  var yyyy = today.getFullYear();
+  function deepCopyStyles() {
+    const clonedStyles = [];
+    for (let style of cachedStyles.list || []) {
+      style = Object.assign({}, style);
+      style.sections = style.sections.slice();
+      for (let i = 0, section; (section = style.sections[i]); i++) {
+        const copy = style.sections[i] = Object.assign({}, section);
+        for (let propName in copy) {
+          const prop = copy[propName];
+          if (prop instanceof Array) {
+            copy[propName] = prop.slice();
+          }
+        }
+      }
+      clonedStyles.push(style);
+    }
+    return clonedStyles;
+  }
 
-  dd = dd.substr(-2);
-  mm = mm.substr(-2);
+  function limitString(s, limit = 100) {
+    return s.length <= limit ? s : s.substr(0, limit) + '...';
+  }
 
-  today = mm + '-' + dd + '-' + yyyy;
-
-  return 'stylus-' + today + STYLISH_DUMPFILE_EXTENSION;
+  function reportNameChange(oldStyle, newStyle) {
+    return newStyle.name != oldStyle.name
+      ? oldStyle.name + ' —> ' + newStyle.name
+      : oldStyle.name;
+  }
 }
 
 document.getElementById('file-all-styles').onclick = () => {
   getStyles({}, function (styles) {
-    let text = JSON.stringify(styles, null, '\t');
-    let fileName = generateFileName() || STYLISH_DEFAULT_SAVE_NAME;
+    const text = JSON.stringify(styles, null, '\t');
+    const fileName = generateFileName();
 
-    let url = 'data:text/plain;charset=utf-8,' + encodeURIComponent(text);
+    const url = 'data:text/plain;charset=utf-8,' + encodeURIComponent(text);
     // for long URLs; https://github.com/schomery/stylish-chrome/issues/13#issuecomment-284582600
     fetch(url)
     .then(res => res.blob())
@@ -103,46 +234,51 @@ document.getElementById('file-all-styles').onclick = () => {
       a.dispatchEvent(new MouseEvent('click'));
     });
   });
+
+  function generateFileName() {
+    const today = new Date();
+    const dd = ('0' + today.getDate()).substr(-2);
+    const mm = ('0' + (today.getMonth() + 1)).substr(-2);
+    const yyyy = today.getFullYear();
+    return `stylus-${mm}-${dd}-${yyyy}${STYLUS_BACKUP_FILE_EXT}`;
+  }
 };
 
 
 document.getElementById('unfile-all-styles').onclick = () => {
-  importFromFile({fileTypeFilter: STYLISH_DUMPFILE_EXTENSION});
+  importFromFile({fileTypeFilter: STYLUS_BACKUP_FILE_EXT});
 };
 
-const dropTarget = Object.assign(document.body, {
-  ondragover: event => {
+Object.assign(document.body, {
+  ondragover(event) {
     const hasFiles = event.dataTransfer.types.includes('Files');
     event.dataTransfer.dropEffect = hasFiles || event.target.type == 'search' ? 'copy' : 'none';
-    dropTarget.classList.toggle('dropzone', hasFiles);
+    this.classList.toggle('dropzone', hasFiles);
     if (hasFiles) {
       event.preventDefault();
-      clearTimeout(dropTarget.fadeoutTimer);
-      dropTarget.classList.remove('fadeout');
+      clearTimeout(this.fadeoutTimer);
+      this.classList.remove('fadeout');
     }
   },
-  ondragend: event => {
-    dropTarget.classList.add('fadeout');
-    // transitionend event may not fire if the user switched to another tab so we'll use a timer
-    clearTimeout(dropTarget.fadeoutTimer);
-    dropTarget.fadeoutTimer = setTimeout(() => {
-      dropTarget.classList.remove('dropzone', 'fadeout');
-    }, 250);
+  ondragend(event) {
+    this.classList.add('fadeout');
+    this.addEventListener('animationend', function _() {
+      this.removeEventListener('animationend', _);
+      this.style.animationDuration = '';
+      this.classList.remove('dropzone', 'fadeout');
+    });
   },
-  ondragleave: event => {
+  ondragleave(event) {
     // Chrome sets screen coords to 0 on Escape key pressed or mouse out of document bounds
     if (!event.screenX && !event.screenX) {
-      dropTarget.ondragend();
+      this.ondragend();
     }
   },
-  ondrop: event => {
+  ondrop(event) {
+    this.ondragend();
     if (event.dataTransfer.files.length) {
       event.preventDefault();
-      importFromFile({file: event.dataTransfer.files[0]}).then(() => {
-        dropTarget.classList.remove('dropzone');
-      });
-    } else {
-      dropTarget.ondragend();
+      importFromFile({file: event.dataTransfer.files[0]});
     }
   },
 });
diff --git a/manage.css b/manage.css
index 9afe0ff0..50204be8 100644
--- a/manage.css
+++ b/manage.css
@@ -111,9 +111,12 @@ a.homepage {
   display: inline;
 }
 
-.applies-to-extra summary {
+summary {
   font-weight: bold;
   cursor: pointer;
+}
+
+.applies-to-extra summary {
   list-style-type: none; /* for FF, allegedly */
 }
 
@@ -255,6 +258,19 @@ fieldset {
   animation-fill-mode: both;
 }
 
+/* post-import report */
+#message-box details:not([data-id="invalid"]) div:hover {
+  background-color: rgba(128, 128, 128, .3);
+}
+
+#message-box details:not(:last-child) {
+    margin-bottom: 1em;
+}
+
+#message-box details small div {
+    margin-left: 1.5em;
+}
+
 @keyframes fadein {
   from {
     opacity: 0;
diff --git a/manage.html b/manage.html
index e561dc06..48b97ed6 100644
--- a/manage.html
+++ b/manage.html
@@ -4,6 +4,7 @@
   <meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
   <title i18n-text="manageTitle"></title>
   <link href="manage.css" rel="stylesheet">
+  <link href="msgbox/msgbox.css" rel="stylesheet">
 
   <template data-id="style">
     <div class="entry">
@@ -121,8 +122,8 @@
 </svg>
 
 <script src="manage.js"></script>
-<script src="openOptions.js"></script>
 <script src="backup/fileSaveLoad.js"></script>
-</body>
+<script src="msgbox/msgbox.js"></script>
 
+</body>
 </html>
diff --git a/manage.js b/manage.js
index 69713813..16ab39a8 100644
--- a/manage.js
+++ b/manage.js
@@ -28,6 +28,11 @@ function initGlobalEvents() {
   $('#check-all-updates').onclick = checkUpdateAll;
   $('#apply-all-updates').onclick = applyUpdateAll;
   $('#search').oninput = searchStyles;
+  $('#manage-options-button').onclick = () => chrome.runtime.openOptionsPage();
+  $('#manage-shortcuts-button').onclick = configureCommands.open;
+  $('#editor-styles-button').onclick = () => openURL({
+    url: 'https://userstyles.org/styles/browse/chrome-extension',
+  });
 
   // focus search field on / key
   document.onkeypress = event => {
@@ -233,11 +238,7 @@ class EntryOnClick {
 function handleUpdate(style, {reason} = {}) {
   const element = createStyleElement(style);
   const oldElement = $(`[style-id="${style.id}"]`, installed);
-  element.addEventListener('animationend', function _() {
-    element.removeEventListener('animationend', _);
-    element.classList.remove('highlight');
-  });
-  element.classList.add('highlight');
+  highlightElement(element);
   if (!oldElement) {
     installed.appendChild(element);
   } else {
@@ -247,11 +248,7 @@ function handleUpdate(style, {reason} = {}) {
       $('.update-note', element).innerHTML = t('updateCompleted');
     }
   }
-  // align to the top/bottom of the visible area if wasn't visible
-  const bounds = element.getBoundingClientRect();
-  if (bounds.top < 0 || bounds.top > innerHeight - bounds.height) {
-    element.scrollIntoView(bounds.top < 0 );
-  }
+  scrollElementIntoView(element);
 }
 
 
@@ -466,6 +463,24 @@ function getClickedStyleElement(event) {
 }
 
 
+function scrollElementIntoView(element) {
+  // align to the top/bottom of the visible area if wasn't visible
+  const bounds = element.getBoundingClientRect();
+  if (bounds.top < 0 || bounds.top > innerHeight - bounds.height) {
+    element.scrollIntoView(bounds.top < 0);
+  }
+}
+
+
+function highlightElement(element) {
+  element.addEventListener('animationend', function _() {
+    element.removeEventListener('animationend', _);
+    element.classList.remove('highlight');
+  });
+  element.classList.add('highlight');
+}
+
+
 function rememberScrollPosition() {
   history.replaceState({scrollY}, document.title);
 }
diff --git a/msgbox/msgbox.css b/msgbox/msgbox.css
new file mode 100644
index 00000000..e3126d73
--- /dev/null
+++ b/msgbox/msgbox.css
@@ -0,0 +1,102 @@
+#message-box {
+  top: 3rem;
+  right: 3rem;
+  min-width: 10rem;
+  max-width: 50vw;
+  min-height: 5rem;
+  max-height: 90vh;
+  position: fixed;
+  display: flex;
+  box-shadow: 5px 5px 50px rgba(0, 0, 0, 0.35);
+  animation: fadein .25s ease-in-out;
+  flex-direction: column;
+  z-index: 9999990;
+}
+
+#message-box > * {
+  z-index: 9999991;
+  background-color: white;
+}
+
+#message-box.fadeout {
+  animation: fadeout .5s ease-in-out;
+}
+
+#message-box::before {
+  position: fixed;
+  content: "";
+  top: 0;
+  left: 0;
+  right: 0;
+  bottom: 0;
+  background-color: rgba(0, 0, 0, .25);
+}
+
+#message-box.big {
+  max-width: none;
+  left: 3rem;
+}
+
+#message-box-title {
+  font-weight: bold;
+  background-color: rgb(145, 208, 198);
+  padding: .75rem 50px .75rem .75rem;
+  font-size: 1rem;
+}
+
+#message-box-title::before {
+  content: "";
+  width: 0;
+  height: 0;
+  padding: 0 32px 32px 0;
+  background: url(/32.png);
+  display: inline-block;
+  vertical-align: middle;
+  margin-right: .5rem;
+}
+
+#message-box-close-icon {
+  cursor: pointer;
+  width: 8px;
+  height: 8px;
+  border: 8px solid transparent;
+  position: absolute;
+  right: 0;
+  top: 0;
+  background: linear-gradient(-45deg, transparent 5px, black 5px, black 6px, transparent 6.5px) no-repeat, linear-gradient(45deg, transparent 5px, black 5px, black 6px, transparent 6.5px) no-repeat;
+}
+
+#message-box-contents {
+  overflow: auto;
+  padding: .75rem;
+  position: relative;
+  flex-grow: 9;
+}
+
+#message-box-buttons {
+  padding: .75rem;
+  background-color: #f0f0f0;
+}
+
+#message-box-buttons button:not(:last-child) {
+  margin-right: 1em;
+}
+
+@keyframes fadein {
+  from {
+    opacity: 0;
+  }
+  to {
+    opacity: 1;
+  }
+}
+
+@keyframes fadeout {
+  from {
+    opacity: 1;
+  }
+  to {
+    opacity: 0;
+  }
+}
+
diff --git a/msgbox/msgbox.js b/msgbox/msgbox.js
new file mode 100644
index 00000000..3cafe8e6
--- /dev/null
+++ b/msgbox/msgbox.js
@@ -0,0 +1,64 @@
+'use strict';
+
+function messageBox({title, contents, buttons, onclick}) {
+  // keep the same reference to be able to remove the listener later
+  messageBox.close = messageBox.close || close;
+  if (messageBox.element) {
+    messageBox.element.remove();
+  }
+  const id = 'message-box';
+  const putAs = typeof contents == 'string' ? 'innerHTML' : 'appendChild';
+  messageBox.element = $element({id, appendChild: [
+    $element({id: `${id}-title`, innerHTML: title}),
+    $element({id: `${id}-close-icon`, onclick: messageBox.close}),
+    $element({id: `${id}-contents`, [putAs]: contents}),
+    $element({id: `${id}-buttons`,
+      onclick: relayButtonClick,
+      appendChild: (buttons || []).map(textContent =>
+        textContent && $element({tag: 'button', textContent}))
+    }),
+  ]});
+  show();
+  return messageBox.element;
+
+  function show() {
+    document.body.appendChild(messageBox.element);
+    document.addEventListener('keydown', messageBox.close);
+  }
+
+  function close(event) {
+    if ((!event
+    || event.type == 'click'
+    || event.keyCode == 27 && !event.altKey && !event.ctrlKey && !event.shiftKey && !event.metaKey)
+    && messageBox.element) {
+      const box = messageBox.element;
+      box.classList.add('fadeout');
+      box.addEventListener('animationend', function _() {
+        box.removeEventListener('animationend', _);
+        box.remove();
+      });
+      document.removeEventListener('keydown', messageBox.close);
+      $(`#${id}-buttons`).onclick = null;
+      messageBox.element = null;
+    }
+  }
+
+  function relayButtonClick(event) {
+    const button = event.target.closest('button');
+    if (button) {
+      close();
+      if (onclick) {
+        onclick([...this.children].indexOf(button));
+      }
+    }
+  }
+
+  function $element(opt) {
+    const element = document.createElement(opt.tag || 'div');
+    (opt.appendChild instanceof Array ? opt.appendChild : [opt.appendChild])
+      .forEach(child => child && element.appendChild(child));
+    delete opt.appendChild;
+    delete opt.tag;
+    return Object.assign(element, opt);
+  }
+}
diff --git a/openOptions.js b/openOptions.js
deleted file mode 100644
index 24a73fb7..00000000
--- a/openOptions.js
+++ /dev/null
@@ -1,20 +0,0 @@
-/* globals configureCommands */
-'use strict';
-
-document.querySelector('#manage-options-button').addEventListener("click", function() {
-    if (chrome.runtime.openOptionsPage) {
-        // Supported (Chrome 42+)
-        chrome.runtime.openOptionsPage();
-    } else {
-        // Fallback
-        window.open(chrome.runtime.getURL('options/index.html'));
-    }
-});
-
-document.querySelector('#manage-shortcuts-button').addEventListener("click", configureCommands.open);
-
-document.querySelector('#editor-styles-button').addEventListener("click", function() {
-    chrome.tabs.create({
-        'url': 'https://userstyles.org/styles/browse/chrome-extension'
-    });
-});
diff --git a/storage.js b/storage.js
index 7889832a..2085fd30 100644
--- a/storage.js
+++ b/storage.js
@@ -256,23 +256,28 @@ function saveStyle(style, {notify = true} = {}) {
 			const tx = db.transaction(['styles'], 'readwrite');
 			const os = tx.objectStore('styles');
 
+			const id = style.id !== undefined && style.id !== null ? Number(style.id) : null;
 			const reason = style.reason;
 			delete style.method;
 			delete style.reason;
 
 			// Update
-			if (style.id) {
-				style.id = Number(style.id);
-				os.get(style.id).onsuccess = eventGet => {
+			if (id != null) {
+				style.id = id;
+				os.get(id).onsuccess = eventGet => {
+					const existed = !!eventGet.target.result;
 					const oldStyle = Object.assign({}, eventGet.target.result);
 					const codeIsUpdated = 'sections' in style && !styleSectionsEqual(style, oldStyle);
 					style = Object.assign(oldStyle, style);
 					addMissingStyleTargets(style);
 					os.put(style).onsuccess = eventPut => {
 						style.id = style.id || eventPut.target.result;
-						invalidateCache(notify, {updated: style});
+						invalidateCache(notify, existed ? {updated: style} : {added: style});
 						if (notify) {
-							notifyAllTabs({method: 'styleUpdated', style, codeIsUpdated, reason});
+							notifyAllTabs({
+								method: existed ? 'styleUpdated' : 'styleAdded',
+								style, codeIsUpdated, reason,
+							});
 						}
 						resolve(style);
 					};
@@ -294,8 +299,10 @@ function saveStyle(style, {notify = true} = {}) {
 			os.add(style).onsuccess = event => {
 				// Give it the ID that was generated
 				style.id = event.target.result;
-				invalidateCache(true, {added: style});
-				notifyAllTabs({method: 'styleAdded', style, reason});
+				invalidateCache(notify, {added: style});
+				if (notify) {
+					notifyAllTabs({method: 'styleAdded', style, reason});
+				}
 				resolve(style);
 			};
 		});
@@ -320,17 +327,19 @@ function enableStyle(id, enabled) {
 }
 
 
-function deleteStyle(id) {
-  return new Promise(resolve =>
-    getDatabase(db => {
-      const tx = db.transaction(['styles'], 'readwrite');
-      const os = tx.objectStore('styles');
-      os.delete(Number(id)).onsuccess = event => {
-        invalidateCache(true, {deletedId: id});
-        notifyAllTabs({method: 'styleDeleted', id});
-        resolve(id);
-      };
-    }));
+function deleteStyle(id, {notify = true} = {}) {
+	return new Promise(resolve =>
+		getDatabase(db => {
+			const tx = db.transaction(['styles'], 'readwrite');
+			const os = tx.objectStore('styles');
+			os.delete(Number(id)).onsuccess = event => {
+				invalidateCache(notify, {deletedId: id});
+				if (notify) {
+					notifyAllTabs({method: 'styleDeleted', id});
+				}
+				resolve(id);
+			};
+		}));
 }
 
 
@@ -371,8 +380,8 @@ function getType(o) {
 		return typeof o;
 	}
 	// with the persistent cachedStyles the Array reference is usually different
-  // so let's check for e.g. type of 'every' which is only present on arrays
-  // (in the context of our extension)
+	// so let's check for e.g. type of 'every' which is only present on arrays
+	// (in the context of our extension)
 	if (o instanceof Array || typeof o.every == 'function') {
 		return 'array';
 	}