feat(lib): throw error if browser does not support parsing methods

remarkablemark · Nov 6, 2019 · de327af · de327af
1 parent 3f3e514
commit de327af
Showing 1 changed file with 43 additions and 48 deletions.
diff --git a/lib/domparser.js b/lib/domparser.js
@@ -14,13 +14,24 @@ var VOID_ELEMENTS_REGEX = /<(area|base|br|col|embed|hr|img|input|keygen|link|men
 var isIE9 = utilities.isIE(9);
 var isIE = isIE9 || utilities.isIE();
 
+// falls back to `parseFromString` if `createHTMLDocument` cannot be used
+var parseFromDocument = function() {
+  throw new Error(
+    'This browser does not support `document.implementation.createHTMLDocument`'
+  );
+};
+
+var parseFromString = function() {
+  throw new Error(
+    'This browser does not support `DOMParser.prototype.parseFromString`'
+  );
+};
+
 /**
  * DOMParser (performance: slow).
  *
  * @see https://developer.mozilla.org/docs/Web/API/DOMParser#Parsing_an_SVG_or_HTML_document
  */
-var parseFromString;
-
 if (typeof window.DOMParser === 'function') {
   var domParser = new window.DOMParser();
 
@@ -35,7 +46,7 @@ if (typeof window.DOMParser === 'function') {
    * @param  {string} [tagName] - The element to render the HTML (with 'body' as fallback).
    * @return {HTMLDocument}
    */
-  parseFromString = function domStringParser(html, tagName) {
+  parseFromString = function(html, tagName) {
     if (tagName) {
       html = '<' + tagName + '>' + html + '</' + tagName + '>';
     }
@@ -47,20 +58,20 @@ if (typeof window.DOMParser === 'function') {
 
     return domParser.parseFromString(html, mimeType);
   };
+
+  parseFromDocument = parseFromString;
 }
 
 /**
  * DOMImplementation (performance: fair).
  *
  * @see https://developer.mozilla.org/docs/Web/API/DOMImplementation/createHTMLDocument
  */
-var parseFromDocument;
-
-if (typeof document.implementation === 'object') {
+if (document.implementation) {
   // title parameter is required in IE
   // https://msdn.microsoft.com/en-us/library/ff975457(v=vs.85).aspx
   var doc = document.implementation.createHTMLDocument(
-    isIE ? 'HTML_DOM_PARSER_TITLE' : undefined
+    isIE ? 'html-dom-parser' : undefined
   );
 
   /**
@@ -70,7 +81,7 @@ if (typeof document.implementation === 'object') {
    * @param  {string} [tagName] - The element to render the HTML (with 'body' as fallback).
    * @return {HTMLDocument}
    */
-  parseFromDocument = function createHTMLDocument(html, tagName) {
+  parseFromDocument = function(html, tagName) {
     if (tagName) {
       doc.documentElement.getElementsByTagName(tagName)[0].innerHTML = html;
       return doc;
@@ -93,8 +104,8 @@ if (typeof document.implementation === 'object') {
  *
  * @see https://developer.mozilla.org/docs/Web/HTML/Element/template
  */
-var parseFromTemplate;
 var template = document.createElement('template');
+var parseFromTemplate;
 
 if (template.content) {
   /**
@@ -103,15 +114,12 @@ if (template.content) {
    * @param  {string} html - The HTML string.
    * @return {NodeList}
    */
-  parseFromTemplate = function templateParser(html) {
+  parseFromTemplate = function(html) {
     template.innerHTML = html;
     return template.content.childNodes;
   };
 }
 
-// fallback document parser
-var parseWithFallback = parseFromDocument || parseFromString;
-
 /**
  * Parses HTML string to DOM nodes.
  *
@@ -132,58 +140,45 @@ function domparser(html) {
 
   switch (firstTagName) {
     case HTML:
-      if (parseFromString) {
-        doc = parseFromString(html);
-
-        // the created document may come with filler head/body elements,
-        // so make sure to remove them if they don't actually exist
-        if (!HEAD_TAG_REGEX.test(html)) {
-          element = doc.getElementsByTagName(HEAD)[0];
-          if (element) {
-            element.parentNode.removeChild(element);
-          }
+      doc = parseFromString(html);
+
+      // the created document may come with filler head/body elements,
+      // so make sure to remove them if they don't actually exist
+      if (!HEAD_TAG_REGEX.test(html)) {
+        element = doc.getElementsByTagName(HEAD)[0];
+        if (element) {
+          element.parentNode.removeChild(element);
         }
+      }
 
-        if (!BODY_TAG_REGEX.test(html)) {
-          element = doc.getElementsByTagName(BODY)[0];
-          if (element) {
-            element.parentNode.removeChild(element);
-          }
+      if (!BODY_TAG_REGEX.test(html)) {
+        element = doc.getElementsByTagName(BODY)[0];
+        if (element) {
+          element.parentNode.removeChild(element);
         }
-
-        return doc.getElementsByTagName(HTML);
       }
-      break;
+
+      return doc.getElementsByTagName(HTML);
 
     case HEAD:
     case BODY:
-      if (parseWithFallback) {
-        elements = parseWithFallback(html).getElementsByTagName(firstTagName);
+      elements = parseFromDocument(html).getElementsByTagName(firstTagName);
 
-        // account for possibility of sibling
-        if (BODY_TAG_REGEX.test(html) && HEAD_TAG_REGEX.test(html)) {
-          return elements[0].parentNode.childNodes;
-        }
-
-        return elements;
+      // if there's a sibling element, then return both elements
+      if (BODY_TAG_REGEX.test(html) && HEAD_TAG_REGEX.test(html)) {
+        return elements[0].parentNode.childNodes;
       }
-      break;
+      return elements;
 
     // low-level tag or text
     default:
       if (parseFromTemplate) {
         return parseFromTemplate(html);
       }
 
-      if (parseWithFallback) {
-        return parseWithFallback(html, BODY).getElementsByTagName(BODY)[0]
-          .childNodes;
-      }
-
-      break;
+      return parseFromDocument(html, BODY).getElementsByTagName(BODY)[0]
+        .childNodes;
   }
-
-  return [];
 }
 
 module.exports = domparser;