title: I'm not getting response in socket from flask server
body: <p><strong>I'm working on socket.io module in flask and I'm not getting a response in the socket after pressing yes, no or maybe button</strong><br>Here is my code<br><br>html code</p>
  
  <pre><code>&gt; &lt;!DOCTYPE html&gt;
  &gt;     &lt;html&gt;
  &gt;         &lt;head&gt;
  &gt;             &lt;script type="text/javascript" src="//cdnjs.cloudflare.com/ajax/libs/socket.io/1.3.6/socket.io.min.js"&gt;&lt;/script&gt;
  &gt;             &lt;script type="text/javascript" src="{{ url_for('static', filename='index.js') }}"&gt;&lt;/script&gt;
  &gt;             &lt;title&gt;Vote&lt;/title&gt;
  &gt;         &lt;/head&gt;
  &gt;         &lt;body&gt;
  &gt;             &lt;ul id="votes"&gt;
  &gt;             &lt;/ul&gt;
  &gt;             &lt;hr&gt;
  &gt;             &lt;button data-vote="yes"&gt;Yes&lt;/button&gt;
  &gt;             &lt;button data-vote="no"&gt;No&lt;/button&gt;
  &gt;             &lt;button data-vote="maybe"&gt;Maybe&lt;/button&gt;
  &gt;         &lt;/body&gt;
  &gt;     &lt;/html&gt;
  </code></pre>
  
  <p>This is my js code</p>
  
  <pre><code> document.addEventListener('DOMContentLoaded', () =&gt; {
  
          // Connect to websocket
          var socket = io.connect(location.protocol + '//' + document.domain + ':' + location.port);
  
          // When connected, configure buttons
          socket.on('connect', () =&gt; {
  
              // Each button should emit a "submit vote" event
              document.querySelectorAll('button').forEach(button =&gt; {
                  button.onclick = () =&gt; {
                      const selection = button.dataset.vote;
                      socket.emit('submit vote', {'selection': selection});
                  };
              });
          });
  
          // When a new vote is announced, add to the unordered list
          socket.on('announce vote', data =&gt; {
              const li = document.createElement('li');
              li.innerHTML = `Vote recorded: ${data.selection}`;
              document.querySelector('#votes').append(li);
          });
      });
  </code></pre>
  
  <p>This is my python code</p>
  
  <pre><code>import os
  import requests
  
  from flask import Flask, jsonify, render_template, request
  from flask_socketio import SocketIO, emit
  
  app = Flask(__name__)
  app.config["SECRET_KEY"] = os.getenv("SECRET_KEY")
  socketio = SocketIO(app)
  
  @app.route("/")
  def index():
      return render_template("index.html")
  
  @socketio.on("submit vote")
  def vote(data):
      selection = data["selection"]
      emit("announce vote", {"selection": selection}, broadcast=True)
  </code></pre>
  
  <blockquote>
    <p>127.0.0.1 - - [06/Mar/2019 23:48:55] "GET / HTTP/1.1" 200 -
    127.0.0.1 - - [06/Mar/2019 23:48:55] "GET /static/index.js HTTP/1.1" 200 -
    127.0.0.1 - - [06/Mar/2019 23:48:56] "GET /socket.io/?EIO=3&amp;transport=polling&amp;t=1551896336110-0 HTTP/1.1" 200 -
    127.0.0.1 - - [06/Mar/2019 23:49:56] "GET /socket.io/?EIO=3&amp;transport=polling&amp;t=1551896336245-1&amp;sid=7d3a45fe719e4e92a2b60728ff734cdf
    HTTP/1.1" 400 -
    127.0.0.1 - - [06/Mar/2019 23:49:56] "GET /favicon.ico HTTP/1.1" 404 -
    127.0.0.1 - - [06/Mar/2019 23:49:56] "POST /socket.io/?EIO=3&amp;transport=polling&amp;t=1551896337783-2&amp;sid=7d3a45fe719e4e92a2b60728ff734cdf
    HTTP/1.1" 400 -
    127.0.0.1 - - [06/Mar/2019 23:49:56] "POST /socket.io/?EIO=3&amp;transport=polling&amp;t=1551896396273-3&amp;sid=7d3a45fe719e4e92a2b60728ff734cdf
    HTTP/1.1" 400 -
    127.0.0.1 - - [06/Mar/2019 23:49:57] "GET /socket.io/?EIO=3&amp;transport=polling&amp;t=1551896397551-4 HTTP/1.1" 200 -
    127.0.0.1 - - [06/Mar/2019 23:50:56] "GET /socket.io/?EIO=3&amp;transport=polling&amp;t=1551896397576-5&amp;sid=42e86974ded740ed8ee99266e917048e
    HTTP/1.1" 200 -
    127.0.0.1 - - [06/Mar/2019 23:50:56] "POST /socket.io/?EIO=3&amp;transport=polling&amp;t=1551896423047-6&amp;sid=42e86974ded740ed8ee99266e917048e
    HTTP/1.1" 400 -
    127.0.0.1 - - [06/Mar/2019 23:50:56] "GET /socket.io/?EIO=3&amp;transport=polling&amp;t=1551896456270-7&amp;sid=42e86974ded740ed8ee99266e917048e
    HTTP/1.1" 400 -
    127.0.0.1 - - [06/Mar/2019 23:50:57] "POST /socket.io/?EIO=3&amp;transport=polling&amp;t=1551896457043-8&amp;sid=42e86974ded740ed8ee99266e917048e
    HTTP/1.1" 400 -
    127.0.0.1 - - [06/Mar/2019 23:50:59] "GET /socket.io/?EIO=3&amp;transport=polling&amp;t=1551896459040-9 HTTP/1.1" 200 -
    127.0.0.1 - - [06/Mar/2019 23:51:56] "GET /socket.io/?EIO=3&amp;transport=polling&amp;t=1551896459067-10&amp;sid=b782019c299b4bc5a913934763b09059
    HTTP/1.1" 200 -
    127.0.0.1 - - [06/Mar/2019 23:51:56] "POST /socket.io/?EIO=3&amp;transport=polling&amp;t=1551896485040-11&amp;sid=b782019c299b4bc5a913934763b09059
    HTTP/1.1" 400 -
    127.0.0.1 - - [06/Mar/2019 23:51:56] "GET /socket.io/?EIO=3&amp;transport=polling&amp;t=1551896516257-12&amp;sid=b782019c299b4bc5a913934763b09059
    HTTP/1.1" 400 -
    127.0.0.1 - - [06/Mar/2019 23:51:57] "POST /socket.io/?EIO=3&amp;transport=polling&amp;t=1551896517043-13&amp;sid=b782019c299b4bc5a913934763b09059
    HTTP/1.1" 400 -
    127.0.0.1 - - [06/Mar/2019 23:51:58] "GET /socket.io/?EIO=3&amp;transport=polling&amp;t=1551896518044-14 HTTP/1.1" 200 -
    127.0.0.1 - - [06/Mar/2019 23:52:56] "GET /socket.io/?EIO=3&amp;transport=polling&amp;t=1551896518072-15&amp;sid=62c3c894db304b538f830b5036e42b6c
    HTTP/1.1" 200 -
    127.0.0.1 - - [06/Mar/2019 23:52:56] "POST /socket.io/?EIO=3&amp;transport=polling&amp;t=1551896544039-16&amp;sid=62c3c894db304b538f830b5036e42b6c
    HTTP/1.1" 400 -</p>
  </blockquote>