app.post is returning 404 in Express/ Node.js

Question

I am learning NodeJS by following tutorials available online. Recently, I am working on a Decision making system that usis Twitter Sentimental analysis to conclude a choice. I am using Express and Node.js to complete the application. I have followed the tutorial and completed the application. However, I cant make it run.

I tried debugging the code and found that my Jquery.post() is not functioning correctly. The debugger is not making a call to $.post or ajax method. As a result, my "/search" route is not calling. After clicking the Decision button, the system does not perform anything. The following is the code for the application.

index.jade

title= title
    meta(charset='utf-8')
    meta(name='viewport', content='width=device-width, initial-scale=1.0')
    meta(name='description', content='')
    meta(name='author', content='Michael Herman')
    link(href='http://netdna.bootstrapcdn.com/bootswatch/3.1.0/yeti/bootstrap.min.css', rel='stylesheet', media='screen')
    link(href='/stylesheets/main.css', rel='stylesheet', media='screen')
  body
    .container
      .jumbotron
        h1 Need to make a decision?
        p.lead Use Twitter sentiment analysis.
        br
        br
        .form-container
          form(action='', method='post')
            input#choice1.choice(type='text', data-choice='1', placeholder='Choice #1...', name='choice1')
            input#choice2.choice(type='text', data-choice='2', placeholder='Choice #2...', name='choice2')
            input#decision.btn.btn-success.btn-lg(type='submit', value='Decide!')
        br
        br
        .decision-container
          p#status
          p#decision-text
          p#score
          input#again.btn.btn-success.btn-lg(value='Again?')
    script(src='http://code.jquery.com/jquery-1.11.0.min.js')
    script(src='http://netdna.bootstrapcdn.com/bootstrap/3.1.1/js/bootstrap.min.js')
    script(src='javascripts/main.js')

app.js

var express = require('express');
var routes = require('./routes');
var http = require('http');
var path = require('path');
var fs = require('fs');
var favicon = require('serve-favicon');
var logger = require('morgan');
var bodyParser = require('body-parser');
var app = express();
app.set('views', path.join(__dirname, 'views'));
app.use(logger('dev'));
app.set('view engine', 'jade');
// uncomment after placing your favicon in /public
//app.use(favicon(path.join(__dirname, 'public', 'favicon.ico')));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.use(express.static(path.join(__dirname, 'public')));
// routes
app.get('/', routes.index);
app.get('/ping', routes.ping);
app.post('/search', routes.search);
app.use(function(req, res, next) {
  var err = new Error('Not Found');
  err.status = 404;
  next(err);
});
if (app.get('env') === 'development') {
  app.use(function(err, req, res, next) {
    res.status(err.status || 500);
    res.render('error', {
      message: err.message,
      error: err
    });
  });
}
app.use(function(err, req, res, next) {
  res.status(err.status || 500);
  res.render('error', {
    message: err.message,
    error: {}
  });
});
module.exports=app;

Index.js

var path = require("path");
var twit = require('twit');
var sentimental = require('Sentimental');

exports.index = function(req, res){
  res.render('index', { title: "Twit-Decision"});
};

exports.ping = function(req, res){
  res.send("pong!", 200);
};

exports.search = function(req, res) {
  // grab the request from the client
  var choices = JSON.parse(req.body.choices);
  // grab the current date
  var today = new Date();
  // establish the twitter config (grab your keys at dev.twitter.com)
  var twitter = new twit({
    consumer_key: *******,
    consumer_secret: *******Dbb0dx7Si4,
    access_token: ********t5bJmk,
    access_token_secret: *******lk
  });
  // set highest score
  var highestScore = -Infinity;
  // set highest choice
  var highestChoice = null;
  // create new array
  var array = [];
  // set score
  var score = 0;
  console.log("----------")

  // iterate through the choices array from the request
  for(var i = 0; i < choices.length; i++) {
    (function(i) {
    // add choice to new array
    array.push(choices[i])
    // grad 20 tweets from today
    twitter.get('search/tweets', {q: '' + choices[i] + ' since:' + today.getFullYear() + '-' + 
      (today.getMonth() + 1) + '-' + today.getDate(), count:20}, function(err, data) {
        // perfrom sentiment analysis (see below)
        score = performAnalysis(data['statuses']);
        console.log("score:", score)
        console.log("choice:", choices[i])
        //  determine winner
        if(score > highestScore) {
          highestScore = score;
          highestChoice = choices[i];
          console.log("winner:",choices[i])
        }
        console.log("")
      });
    })(i)
  }
  // send response back to the server side; why the need for the timeout?
  setTimeout(function() { res.end(JSON.stringify({'score': highestScore, 'choice': highestChoice})) }, 5000);   
};

function performAnalysis(tweetSet) {
  //set a results variable
  var results = 0;
  // iterate through the tweets, pulling the text, retweet count, and favorite count
  for(var i = 0; i < tweetSet.length; i++) {
    tweet = tweetSet[i]['text'];
    retweets = tweetSet[i]['retweet_count'];
    favorites = tweetSet[i]['favorite_count'];
    // remove the hashtag from the tweet text
    tweet = tweet.replace('#', '');
    // perfrom sentiment on the text
    var score = sentimental.analyze(tweet)['score'];
    // calculate score
    results += score;
    if(score > 0){
      if(retweets > 0) {
        results += (Math.log(retweets)/Math.log(2));
      }
      if(favorites > 0) {
        results += (Math.log(favorites)/Math.log(2));
      }
    }
    else if(score < 0){
      if(retweets > 0) {
        results -= (Math.log(retweets)/Math.log(2));
      }
      if(favorites > 0) {
        results -= (Math.log(favorites)/Math.log(2));
      }
    }
    else {
      results += 0;
    }
  }
  // return score
  results = results / tweetSet.length;
  return results
}

Main.js

$(function () {

  // highest # of choices (inputs) allowed
  window.highestChoice = 2;
  // hide again button on page load
  $("#again").hide();

  var goDecide = function(e) {
    // prevent default browser behavior upon submit
    e.preventDefault();
    console.log("--------------- Inside GODECIDE----------------");
    // erase old values
    $("#status").text('');
    $("#score").text('');
    // hide decision text
    $("#decision-text").hide();
    $("#again").hide();
    // display processing text, update color to black in case of an error
    $("#status").css("color", "black");
    $("#status").text("Processing ...");
    // create variable to see if any of the inputs are input
    var anyEmpty = false;
    // array to hold inputs
    var choices = [];
    // grab values, add to choices array
    for(var i = 1; i <= window.highestChoice; i++) {
      var choiceValue = $("#choice"+i).val();
      if(choiceValue == '') {
        anyEmpty = true;
      } else {
        if(choices.indexOf(choiceValue) == -1) {
          choices.push(choiceValue);
        }
      }
    }
        console.log("--------------- CHOICES LOOP COMPLETED---------------");

    // Handling *some* errors
    if(!anyEmpty) {

      if($("#choice1").val() != $("#choice2").val()) {
        // send values to server side for processing, wait for callback, getting AJAXy
          $.ajax({
            type: 'post',
            url: 'http://localhost:3000/search',
            data: {'choices': JSON.stringify(choices)},
            contentType: "application/json; charset=utf-8",
            success: function (data) {
             data = JSON.parse(data);
          // append data to the DOM
          $(".form-container").hide()
          $("#status").text("and the winner is ...");
          $("#decision-text").text(data['choice']);
          $("#score").text('... with a score of ' + data['score'] + '');
          $("#decision-text").fadeIn();
          $("#score").fadeIn();
          $("#again").show()            },
            failure: function(errMsg) {
                        alert("------BAD REQUEST------");
        }        });

 // $.post('http://localhost:3000/search', {'choices': JSON.stringify(choices)}, function(data) {
//           data = JSON.parse(data);
//           // append data to the DOM
//           $(".form-container").hide()
//           $("#status").text("and the winner is ...");
//           $("#decision-text").text(data['choice']);
//           $("#score").text('... with a score of ' + data['score'] + '');
//           $("#decision-text").fadeIn();
//           $("#score").fadeIn();
//           $("#again").show()
//         });
// 



      } else {
        // error code
        $("#status").css("color", "red");
        $("#status").text("Both choices are the same. Try again.");
      }
    } else {
      // error code
      $("#status").css("color", "red");
      $("#status").text("You must enter a value for both choices.");
    }
  }



  // ----- MAIN ----- //

  // on click, run the goDecide function
  $("#decision").click(goDecide);
  // on click new form is shown
  $("#again").click(function() {
    $(".form-container").show()
    $("#again").hide()
    // erase old values
    $("#status").text('');
    $("#score").text('');
    $("#choice1").val('');
    $("#choice2").val('');
    // hide decision text
    $("#decision-text").hide();
  });

});

Console output:

Failed to load resource: the server responded with a status of 400 (Bad Request)

I don't know what I am doing wrong and why my $.post method is not working. I also tried to do the ajax method, but I don't get any result. I researched online and didn't find anything substantial that can solve my issue. I request you to please help me out. Thanks!