View difference between Paste ID: 6VKS6LRE and C8cw8L0w

 var repeatingSpamFunction = null;
 var message = '';
 
 function getElementByXpath(path) {
   return document.evaluate(path, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue;
 }
 
 document.onclick = function(){
   createSpamButton();
 };
 
 function createSpamButton () {
   if(document.getElementById('spamButton') != null)
     return;
   var composeBar = getElementByXpath("//*[@id=\"main\"]/footer/div[1]");
   if(composeBar == null)
     return;
   composeBar.oninput = function(){
     editSpamButton();
   };
 
   var spamButton = document.createElement('button');
   spamButton.setAttribute("id", "spamButton");
   spamButton.innerHTML = 'SPAM';
   spamButton.style.fontSize = '100%';
   spamButton.style.padding = '0px 0px 10px 10px';
   composeBar.append(spamButton);
   editSpamButton();
 }
 
 function sendMessage () {
   var evt = new Event('input', {
     bubbles: true
   });
 
   var input = getElementByXpath("//*[@id=\"main\"]/footer/div[1]/div[2]/div/div[2]");
   input.innerHTML = message;
   input.dispatchEvent(evt);
 
   getElementByXpath("//*[@id=\"main\"]/footer/div[1]/div[3]/button").click();
 }
 
 function doSpam(element) {
   if(element.innerHTML == 'SPAM'){
     var input = getElementByXpath("//*[@id=\"main\"]/footer/div[1]/div[2]/div/div[2]");
     if(input.innerHTML == '' || input.innerHTML == null){
       window.alert('Please Enter a Text to be spammed before using the spam button.');
       return;
     }
     element.innerHTML = 'STOP';
     message = input.innerHTML;
     var interval = parseInt (prompt('Please enter spam-interval:', '500'));
     repeatingSpamFunction = window.setInterval(function(){
       sendMessage();
     }, interval);
   } else {
     element.innerHTML = 'SPAM';
     window.clearInterval(repeatingSpamFunction);
   }
   editSpamButton();
 }
 
 function editSpamButton(){
   var spamButton = document.getElementById('spamButton');
   var input = getElementByXpath("//*[@id=\"main\"]/footer/div[1]/div[2]/div/div[2]");
   if(input.innerHTML == '' || input.innerHTML == null){
     spamButton.style.cursor = 'not-allowed';
     spamButton.style.color = '#D3D3D3';
     spamButton.onclick = null;
   } else {
     spamButton.style.cursor = 'pointer';
     spamButton.style.color = '#039be5';
     spamButton.onclick = function(){
       doSpam(this);
     };
   }
 }