使用javascript模拟左右箭头键事件

function fireKey(el)
{
    //Set key to corresponding code. This one is set to the left arrow key.
    var key = 37;
    if(document.createEventObject)
    {
        var eventObj = document.createEventObject();
        eventObj.keyCode = key;
        el.fireEvent("onkeydown", eventObj);   
    }else if(document.createEvent)
    {
        var eventObj = document.createEvent("Events");
        eventObj.initEvent("keydown", true, true);
        eventObj.which = key;
        el.dispatchEvent(eventObj);
    }
} 

typeOf(document.dispatchEvent) != 'undefined'