Noissue - Remove unnecessary typeof checks in lib/matcher.js

lib/matcher.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 50 matching lines @@
    * @param {RegExpFilter} filter
    */
   add(filter)
   {
     if (this.keywordByFilter.has(filter))
       return;
 
     // Look for a suitable keyword
     let keyword = this.findKeyword(filter);
     let oldEntry = this.filterByKeyword.get(keyword);
-    if (typeof oldEntry == "undefined")
+    if (!oldEntry)
       this.filterByKeyword.set(keyword, filter);
     else if (oldEntry.length == 1)
       this.filterByKeyword.set(keyword, [oldEntry, filter]);
     else
       oldEntry.push(filter);
     this.keywordByFilter.set(filter, keyword);
   },
 
   /**
    * Removes a filter from the matcher
    * @param {RegExpFilter} filter
    */
   remove(filter)
   {
     let keyword = this.keywordByFilter.get(filter);
-    if (typeof keyword == "undefined")
+    if (keyword == null)

[Manish Jethani, 2018/06/12 04:50:27]

keyword can be an empty string, so we must check against null here.

       return;
 
     let list = this.filterByKeyword.get(keyword);
     if (list.length <= 1)
       this.filterByKeyword.delete(keyword);
     else
     {
       let index = list.indexOf(filter);
       if (index >= 0)
       {
@@ skipping 33 matching lines @@
     if (!candidates)
       return result;
 
     let hash = this.filterByKeyword;
     let resultCount = 0xFFFFFF;
     let resultLength = 0;
     for (let i = 0, l = candidates.length; i < l; i++)
     {
       let candidate = candidates[i].substr(1);
       let filters = hash.get(candidate);
-      let count = typeof filters != "undefined" ? filters.length : 0;
+      let count = filters ? filters.length : 0;
       if (count < resultCount ||
           (count == resultCount && candidate.length > resultLength))
       {
         result = candidate;
         resultCount = count;
         resultLength = candidate.length;
       }
     }
     return result;
   },
 
   /**
    * Checks whether a particular filter is being matched against.
    * @param {RegExpFilter} filter
    * @return {boolean}
    */
   hasFilter(filter)
   {
     return this.keywordByFilter.has(filter);
   },
 
   /**
    * Returns the keyword used for a filter, null for unknown filters.
    * @param {RegExpFilter} filter
    * @return {?string}
    */
   getKeywordForFilter(filter)
   {
     let keyword = this.keywordByFilter.get(filter);
-    return typeof keyword != "undefined" ? keyword : null;
+    return keyword != null ? keyword : null;
   },
 
   /**
    * Checks whether the entries for a particular keyword match a URL
    * @param {string} keyword
    * @param {string} location
    * @param {number} typeMask
    * @param {string} docDomain
    * @param {boolean} thirdParty
    * @param {string} sitekey
    * @param {boolean} specificOnly
    * @return {?Filter}
    */
   _checkEntryMatch(keyword, location, typeMask, docDomain, thirdParty, sitekey,
                    specificOnly)
   {
     let list = this.filterByKeyword.get(keyword);
-    if (typeof list == "undefined")
+    if (!list)
       return null;
     for (let i = 0; i < list.length; i++)
     {
       let filter = list[i];
 
       if (specificOnly && filter.isGeneric() &&
           !(filter instanceof WhitelistFilter))
         continue;
 
       if (filter.matches(location, typeMask, docDomain, thirdParty, sitekey))
@@ skipping 224 matching lines @@
 
     return result;
   }
 };
 
 /**
  * Shared CombinedMatcher instance that should usually be used.
  * @type {CombinedMatcher}
  */
 exports.defaultMatcher = new CombinedMatcher();