fix: detection logic in quasi-browser environments

- Always use `window` object for detecting DOM-related types; a
  quasi-browser environment can be loaded on top of a server
  environment.
- Always verify that each property of `window` exists before using
  it for type detection; nothing is guaranteed in a quasi-browser
  environment.
- Refactor to remove redundant `instanceof window.HTMLElement`.

Author: meeber

index.js

@@ -8,16 +8,6 @@ const promiseExists = typeof Promise === 'function';
 /* eslint-disable no-undef */
 const globalObject = typeof self === 'object' ? self : global; // eslint-disable-line id-blacklist
 
-/*
- * All of these attributes must be available on the global object for the current environment
- * to be considered a DOM environment (browser)
- */
-const isDom = typeof window === 'object' &&
-  'document' in window &&
-  'navigator' in window &&
-  'HTMLElement' in window;
-/* eslint-enable */
-
 const symbolExists = typeof Symbol !== 'undefined';
 const mapExists = typeof Map !== 'undefined';
 const setExists = typeof Set !== 'undefined';
@@ -36,6 +26,14 @@ const stringIteratorExists = symbolIteratorExists && typeof String.prototype[Sym
 const stringIteratorPrototype = stringIteratorExists && Object.getPrototypeOf(''[Symbol.iterator]());
 const toStringLeftSliceLength = 8;
 const toStringRightSliceLength = -1;
+const windowExists = typeof window === 'object';
+const windowLocationExists = windowExists && typeof window.location === 'object';
+const windowDocumentExists = windowExists && typeof window.document === 'object';
+const windowNavigatorExists = windowExists && typeof window.navigator === 'object';
+const windowNavigatorMimeTypesExists = windowNavigatorExists && typeof window.navigator.mimeTypes === 'object';
+const windowNavigatorPluginsExists = windowNavigatorExists && typeof window.navigator.plugins === 'object';
+const windowHTMLElementExists = windowExists &&
+  (typeof window.HTMLElement === 'function' || typeof window.HTMLElement === 'object');
 /**
  * ### typeOf (obj)
  *
@@ -109,15 +107,15 @@ export default function typeDetect(obj) {
     return 'Array';
   }
 
-  if (isDom) {
+  if (windowExists) {
     /* ! Spec Conformance
      * (https://html.spec.whatwg.org/multipage/browsers.html#location)
      * WhatWG HTML$7.7.3 - The `Location` interface
      * Test: `Object.prototype.toString.call(window.location)``
      *  - IE <=11 === "[object Object]"
      *  - IE Edge <=13 === "[object Object]"
      */
-    if (obj === globalObject.location) {
+    if (windowLocationExists && obj === window.location) {
       return 'Location';
     }
 
@@ -140,7 +138,7 @@ export default function typeDetect(obj) {
      *  - IE 11 === "[object HTMLDocument]"
      *  - IE Edge <=13 === "[object HTMLDocument]"
      */
-    if (obj === globalObject.document) {
+    if (windowDocumentExists && obj === window.document) {
       return 'Document';
     }
 
@@ -150,7 +148,7 @@ export default function typeDetect(obj) {
      * Test: `Object.prototype.toString.call(navigator.mimeTypes)``
      *  - IE <=10 === "[object MSMimeTypesCollection]"
      */
-    if (obj === (globalObject.navigator || {}).mimeTypes) {
+    if (windowNavigatorMimeTypesExists && obj === window.navigator.mimeTypes) {
       return 'MimeTypeArray';
     }
 
@@ -160,50 +158,52 @@ export default function typeDetect(obj) {
      * Test: `Object.prototype.toString.call(navigator.plugins)``
      *  - IE <=10 === "[object MSPluginsCollection]"
      */
-    if (obj === (globalObject.navigator || {}).plugins) {
+    if (windowNavigatorPluginsExists && obj === window.navigator.plugins) {
       return 'PluginArray';
     }
 
-    /* ! Spec Conformance
-     * (https://html.spec.whatwg.org/multipage/webappapis.html#pluginarray)
-     * WhatWG HTML$4.4.4 - The `blockquote` element - Interface `HTMLQuoteElement`
-     * Test: `Object.prototype.toString.call(document.createElement('blockquote'))``
-     *  - IE <=10 === "[object HTMLBlockElement]"
-     */
-    if (obj instanceof globalObject.HTMLElement && obj.tagName === 'BLOCKQUOTE') {
-      return 'HTMLQuoteElement';
-    }
+    if (windowHTMLElementExists && obj instanceof window.HTMLElement) {
+      /* ! Spec Conformance
+      * (https://html.spec.whatwg.org/multipage/webappapis.html#pluginarray)
+      * WhatWG HTML$4.4.4 - The `blockquote` element - Interface `HTMLQuoteElement`
+      * Test: `Object.prototype.toString.call(document.createElement('blockquote'))``
+      *  - IE <=10 === "[object HTMLBlockElement]"
+      */
+      if (obj.tagName === 'BLOCKQUOTE') {
+        return 'HTMLQuoteElement';
+      }
 
-    /* ! Spec Conformance
-     * (https://html.spec.whatwg.org/#htmltabledatacellelement)
-     * WhatWG HTML$4.9.9 - The `td` element - Interface `HTMLTableDataCellElement`
-     * Note: Most browsers currently adher to the W3C DOM Level 2 spec
-     *       (https://www.w3.org/TR/DOM-Level-2-HTML/html.html#ID-82915075)
-     *       which suggests that browsers should use HTMLTableCellElement for
-     *       both TD and TH elements. WhatWG separates these.
-     * Test: Object.prototype.toString.call(document.createElement('td'))
-     *  - Chrome === "[object HTMLTableCellElement]"
-     *  - Firefox === "[object HTMLTableCellElement]"
-     *  - Safari === "[object HTMLTableCellElement]"
-     */
-    if (obj instanceof globalObject.HTMLElement && obj.tagName === 'TD') {
-      return 'HTMLTableDataCellElement';
-    }
+      /* ! Spec Conformance
+       * (https://html.spec.whatwg.org/#htmltabledatacellelement)
+       * WhatWG HTML$4.9.9 - The `td` element - Interface `HTMLTableDataCellElement`
+       * Note: Most browsers currently adher to the W3C DOM Level 2 spec
+       *       (https://www.w3.org/TR/DOM-Level-2-HTML/html.html#ID-82915075)
+       *       which suggests that browsers should use HTMLTableCellElement for
+       *       both TD and TH elements. WhatWG separates these.
+       * Test: Object.prototype.toString.call(document.createElement('td'))
+       *  - Chrome === "[object HTMLTableCellElement]"
+       *  - Firefox === "[object HTMLTableCellElement]"
+       *  - Safari === "[object HTMLTableCellElement]"
+       */
+      if (obj.tagName === 'TD') {
+        return 'HTMLTableDataCellElement';
+      }
 
-    /* ! Spec Conformance
-     * (https://html.spec.whatwg.org/#htmltableheadercellelement)
-     * WhatWG HTML$4.9.9 - The `td` element - Interface `HTMLTableHeaderCellElement`
-     * Note: Most browsers currently adher to the W3C DOM Level 2 spec
-     *       (https://www.w3.org/TR/DOM-Level-2-HTML/html.html#ID-82915075)
-     *       which suggests that browsers should use HTMLTableCellElement for
-     *       both TD and TH elements. WhatWG separates these.
-     * Test: Object.prototype.toString.call(document.createElement('th'))
-     *  - Chrome === "[object HTMLTableCellElement]"
-     *  - Firefox === "[object HTMLTableCellElement]"
-     *  - Safari === "[object HTMLTableCellElement]"
-     */
-    if (obj instanceof globalObject.HTMLElement && obj.tagName === 'TH') {
-      return 'HTMLTableHeaderCellElement';
+      /* ! Spec Conformance
+       * (https://html.spec.whatwg.org/#htmltableheadercellelement)
+       * WhatWG HTML$4.9.9 - The `td` element - Interface `HTMLTableHeaderCellElement`
+       * Note: Most browsers currently adher to the W3C DOM Level 2 spec
+       *       (https://www.w3.org/TR/DOM-Level-2-HTML/html.html#ID-82915075)
+       *       which suggests that browsers should use HTMLTableCellElement for
+       *       both TD and TH elements. WhatWG separates these.
+       * Test: Object.prototype.toString.call(document.createElement('th'))
+       *  - Chrome === "[object HTMLTableCellElement]"
+       *  - Firefox === "[object HTMLTableCellElement]"
+       *  - Safari === "[object HTMLTableCellElement]"
+       */
+      if (obj.tagName === 'TH') {
+        return 'HTMLTableHeaderCellElement';
+      }
     }
   }