title: Issue with Facebook messenger bot (welcome message and button message)
body: <p>I'm facing 2 issues when developing a Facebook messenger bot, and I'm a newbie to programming.</p>
  
  <ol>
  <li><p>I followed FB's tutorial to add the code - welcome message and deployed it in heroku, but my bot didn't pop up the said message.</p>
  
  <blockquote>
  <pre><code>app.post('/webhook/', function (req, res) {
  let messaging_events = req.body.entry[0].messaging
  for (let i = 0; i &lt; messaging_events.length; i++) {
    let event = req.body.entry[0].messaging[i]
    let sender = event.sender.id
    if (event.message &amp;&amp; event.message.text) {
      let text = event.message.text
      if (text === 'Generic') {
          sendGenericMessage(sender)
          continue
      }
      if (text === 'button') {
          sendbuttonmessage(sender)
          continue
      }
      welcomemessage(sender)
      //sendbuttonmessage(sender)
    }
    if (event.postback) {
      let text = JSON.stringify(event.postback)
      sendTextMessage(sender, "Postback received: "+text.substring(0, 200), token)
      continue
    }
  }
  res.sendStatus(200)   })
  </code></pre>
  </blockquote></li>
  </ol>
  
  <blockquote>
  <pre><code>function welcomemessage (sender) {   let messageData = {
      "setting_type":"call_to_actions",   "thread_state":"new_thread",   "call_to_actions":[
      {
        "message":{
          "text":"Welcome to My Company!"
        }
      }   ] }   request({
      url: 'https://graph.facebook.com/v2.6/me/messages',
      qs: {access_token:token},
        method: 'POST',
        json: {
            recipient: {id:sender},
            message: messageData,
        }   }, function(error, response, body) {
        if (error) {
            console.log('Error sending messages: ', error)
        } else if (response.body.error) {
            console.log('Error: ', response.body.error)
        }   }) }
  </code></pre>
  </blockquote>
  
  <ol start="2">
  <li>How do I pop up another button when ppl clicked them? For example:
  send function <code>sendbuttonmessage(sender)</code> after they click the web url of the button.</li>
  </ol>
  
  <blockquote>
  <pre><code>function sendbuttonmessage (sender) {
      let messageData = {
          "attachment": {
            "type":"template",
            "payload":{
              "template_type":"button",
              "text":"Welcome to Taikoo Place. How can we help?",
              "buttons":[
                {
                  "type":"web_url",
                  "url":"https://peterapparel.parseapp.com",
                  "title":"Show Website"
                },
                {
                  "type":"postback",
                  "title":"Service Lift Booking",
                  "payload":"what"
                  //"payload":"USER_DEFINED_PAYLOAD"
                },
              ]
            }
          }
        }
  </code></pre>
  </blockquote>