这可以做到:

$(document).ready(function() {
    var e = $.Event('keydown', { keyCode: 39 });// right arrow key
    $(document).trigger(e);
});

参考文献:

• JS触发按键事件
• 是否可以通过编程方式模拟按键事件?
• 在JS/jQuery吗?

• JS trigger keydown event
• Is it possible to simulate key press events programmatically?
• Trigger a keypress/keydown/keyup event in JS/jQuery?