Gmail подгружаем следующу страницу

function loadNextPage() {
    triggerEvent(document.querySelector('.ar5.J-J5-Ji'), 'mousedown');
    var _ = document.querySelector('.T-I.J-J5-Ji.amD.T-I-awG.T-I-ax7.T-I-Js-Gs.L3');
    triggerEvent(_, 'mousedown');
    triggerEvent(_, 'mouseup');
}

function triggerEvent(targetElement, eventName) {
    var event = document.createEvent('MouseEvents');
    event.initEvent(eventName);
    targetElement.dispatchEvent(event);
}