code: function nodeCollector_filter(aCallback, aThisObject) {
      if (!aCallback)
        throw new Error(arguments.callee.name + ": No callback specified");
  
      this.nodes = Array.filter(this.nodes, aCallback, aThisObject);
  
      return this;
    }
docs: Filter nodes given by the specified callback function
  
  @param {function} aCallback
  Function to test each element of the array.
  Elements: node, index (optional) , array (optional)
  @param {object} aThisObject
  Object to use as 'this' when executing callback.
  [optional - default: function scope]
  
  @returns The class instance
  @type {object}