Clean IDs and classes from output.

Readability.js

@@ -35,11 +35,12 @@ function Readability(uri, doc, options) {
   this._articleByline = null;
   this._articleDir = null;
 
-  // Configureable options
+  // Configurable options
   this._debug = !!options.debug;
   this._maxElemsToParse = options.maxElemsToParse || this.DEFAULT_MAX_ELEMS_TO_PARSE;
   this._nbTopCandidates = options.nbTopCandidates || this.DEFAULT_N_TOP_CANDIDATES;
   this._wordThreshold = options.wordThreshold || this.DEFAULT_WORD_THRESHOLD;
+  this._classesToPreserve = this.CLASSES_TO_PRESERVE.concat(options.classesToPreserve || []);
 
   // Start with all flags set
   this._flags = this.FLAG_STRIP_UNLIKELYS |
@@ -123,6 +124,10 @@ Readability.prototype = {
 
   DEPRECATED_SIZE_ATTRIBUTE_ELEMS: [ "TABLE", "TH", "TD", "HR", "PRE" ],
 
+  // These are the IDs and classes that readability sets itself.
+  IDS_TO_PRESERVE: [ "readability-content", "readability-page-1" ],
+  CLASSES_TO_PRESERVE: [ "readability-styled", "page" ],
+
   /**
    * Run any post-process modifications to article content as necessary.
    *
@@ -132,6 +137,9 @@ Readability.prototype = {
   _postProcessContent: function(articleContent) {
     // Readability cannot open relative uris so we convert them to absolute uris.
     this._fixRelativeUris(articleContent);
+
+    // Remove IDs and classes.
+    this._cleanIDsAndClasses(articleContent);
   },
 
   /**
@@ -225,6 +233,38 @@ Readability.prototype = {
     }));
   },
 
+  /**
+   * Removes the id="" and class="" attribute from every element in the given
+   * subtree, except those that match IDS_TO_PRESERVE, CLASSES_TO_PRESERVE and
+   * the classesToPreserve array from the options object.
+   *
+   * @param Element
+   * @return void
+   */
+  _cleanIDsAndClasses: function(node) {
+    if (this.IDS_TO_PRESERVE.indexOf(node.id) == -1) {
+      node.removeAttribute("id");
+    }
+
+    var classesToPreserve = this._classesToPreserve;
+    var className = node.className
+      .split(/\s+/)
+      .filter(function(cls) {
+        return classesToPreserve.indexOf(cls) != -1;
+      })
+      .join(" ");
+
+    if (className) {
+      node.className = className;
+    } else {
+      node.removeAttribute("class");
+    }
+
+    for (node = node.firstElementChild; node; node = node.nextElementSibling) {
+      this._cleanIDsAndClasses(node);
+    }
+  },
+
   /**
    * Converts each <a> and <img> uri in the given element to an absolute URI,
    * ignoring #ref URIs.