var src = 'https://cdnjs.cloudflare.com/ajax/libs/chance/1.0.13/chance.min.js';
var script = document.createElement('script');
script.src = src;
script.onload = onGreaseLoad;
document.body.appendChild(script);

function onGreaseLoad() {

    var input = document.querySelector('#user_message');
    function getMsg () {
      return chance.paragraph();
    }

    setInterval(() => {
        console.log('sending message spam');
        input.value = getMsg();
        input.focus();
        input.dispatchEvent(new KeyboardEvent('keydown', { key: "Enter" }));

    }, 1000);
}