Send messages on web.whatsapp.com

send_whatsapp_msg.js

function sendMessage (message) {
  window.InputEvent = window.Event || window.InputEvent;

  var event = new InputEvent('input', {
    bubbles: true
  });

  var textbox = document.querySelector('div._3u328');

  textbox.textContent = message;
  textbox.dispatchEvent(event);

  document.querySelector("button._3M-N-").click();
}

function randomChoice(arr) {
    return arr[Math.floor(arr.length * Math.random())];
}

var choices = ['random', 'messages', 'here'] # will be taken randomly

for(var i=0; i<10; i++)
  sendMessage(randomChoice(choices))