ordering email threads

gistfile1.js

    var histories = [];
    this.state.currentObject.activities.forEach(function(activityHistory) {
      // TYPE FILTER
      if (thisComponent.state.typeFilter && thisComponent.state.typeFilter.indexOf(activityHistory.ActivityType) === -1) {
        return;
      }
      histories.push(activityHistory);
    });

    // Get all the emails
    var emails = [];
    var nonEmails = [];
    histories.forEach(function(history) {
      if ( history.Subject && history.Subject.indexOf('Email:') > -1 ){
        emails.push(history);
      } else {
        nonEmails.push(history);
      }
    })
    var threads = {};
    // Go through all the emails 
    emails.forEach(function(email) {
      var cleanSubject = email.Subject.replace('Email: << ','') // replace both email indicators attached by groove
                                      .replace('Email: >> ','')
                                      .replace('Email: ','')
                                      .replace('re: ','') // thread regardless of response
                                      .replace('Re: ','').trim() || 'No Subject';
      if (threads.hasOwnProperty(cleanSubject)) {
        threads[cleanSubject]['messages'].push(email);
      } else {
        threads[cleanSubject] = {
          isThread: true,
          lastMessageDate: new Date(email.ActivityDate),
          subject: cleanSubject,
          messages: [email] 
        }
      }
    });

    var threadArray = $.map(threads, function(value, index) {
      return value;
    });

    var condensedHistory = threadArray.concat(nonEmails);

    sortedHistory = condensedHistory.sort(function(a,b){
      var aDate, bDate;
      if (a.isThread) {
        aDate = a.lastMessageDate;
      } else {
        aDate = new Date(a.ActivityDate);
      }
      if (b.isThread) {
        bDate = b.lastMessageDate;
      } else {
        bDate = new Date(b.ActivityDate);
      }

      if (aDate > bDate)
        return -1;
      if (aDate < bDate)
        return 1;
      return 0;
    });


    var finalHistory = [];
    sortedHistory.forEach(function(history) {
      if (history.isThread) {
        finalHistory.push(<EmailThread threadData={history} />);  
      } else {
        finalHistory.push(<Activity activityData={history}/>)
      }