Create abstraction class for parsing DOM (#798)

ext/bg/background.html

@@ -37,6 +37,7 @@
         <script src="/bg/js/profile-conditions.js"></script>
         <script src="/bg/js/request-builder.js"></script>
         <script src="/bg/js/template-renderer.js"></script>
+        <script src="/bg/js/simple-dom-parser.js"></script>
         <script src="/bg/js/text-source-map.js"></script>
         <script src="/bg/js/translator.js"></script>
         <script src="/bg/js/util.js"></script>

ext/bg/js/audio-uri-builder.js

@@ -16,6 +16,7 @@
  */
 
 /* global
+ * SimpleDOMParser
  * jp
  */
 
@@ -99,12 +100,23 @@ class AudioUriBuilder {
         });
         const responseText = await response.text();
 
-        const dom = new DOMParser().parseFromString(responseText, 'text/html');
+        const dom = new SimpleDOMParser(responseText);
         for (const row of dom.getElementsByClassName('dc-result-row')) {
             try {
-                const url = row.querySelector('audio>source[src]').getAttribute('src');
-                const reading = row.getElementsByClassName('dc-vocab_kana').item(0).textContent;
-                if (url && reading && (!definition.reading || definition.reading === reading)) {
+                const audio = dom.getElementByTagName('audio', row);
+                if (audio === null) { continue; }
+
+                const source = dom.getElementByTagName('source', audio);
+                if (source === null) { continue; }
+
+                const url = dom.getAttribute(source, 'src');
+                if (url === null) { continue; }
+
+                const readings = dom.getElementsByClassName('dc-vocab_kana');
+                if (readings.length === 0) { continue; }
+
+                const reading = dom.getTextContent(readings[0]);
+                if (reading && (!definition.reading || definition.reading === reading)) {
                     return this.normalizeUrl(url, 'https://www.japanesepod101.com', '/learningcenter/reference/');
                 }
             } catch (e) {
@@ -127,15 +139,18 @@ class AudioUriBuilder {
         });
         const responseText = await response.text();
 
-        const dom = new DOMParser().parseFromString(responseText, 'text/html');
+        const dom = new SimpleDOMParser(responseText);
         try {
             const audio = dom.getElementById(`audio_${definition.expression}:${definition.reading}`);
             if (audio !== null) {
-                const url = audio.getElementsByTagName('source').item(0).getAttribute('src');
-                if (url) {
+                const source = dom.getElementByTagName('source', audio);
+                if (source !== null) {
+                    const url = dom.getAttribute(source, 'src');
+                    if (url !== null) {
                         return this.normalizeUrl(url, 'https://jisho.org', '/search/');
                     }
                 }
+            }
         } catch (e) {
             // NOP
         }

ext/bg/js/simple-dom-parser.js

@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) 2020  Yomichan Authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+class SimpleDOMParser {
+    constructor(content) {
+        this._document = new DOMParser().parseFromString(content, 'text/html');
+    }
+
+    getElementById(id, root=null) {
+        return (root || this._document).querySelector(`[id='${id}']`);
+    }
+
+    getElementByTagName(tagName, root=null) {
+        return (root || this._document).querySelector(tagName);
+    }
+
+    getElementsByTagName(tagName, root=null) {
+        return [...(root || this._document).querySelectorAll(tagName)];
+    }
+
+    getElementsByClassName(className, root=null) {
+        return [...(root || this._document).querySelectorAll(`.${className}`)];
+    }
+
+    getAttribute(element, attribute) {
+        return element.hasAttribute(attribute) ? element.getAttribute(attribute) : null;
+    }
+
+    getTextContent(element) {
+        return element.textContent;
+    }
+}