检查是否从事件处理函数触发了另一个事件

Question

Let's imagine I have an event handler function attached to an image, for example, an onmouseover handler. I don't want this handler run if an onmouseover event is fired by a particular element.

To be more specific, I have an image which being hovered, a menu is popped out. I want to close that menu if the mouse moves out of that image, unless I move the mouse to the menu, which is adjacent to the image.

So something like this in pseudo code:

img.mouseout = function () {
if (otherelement.onmouseover.fired) {
 leave the menu as it is
} 
else 
{
close the menu
}

So how can I check whether another event was fired?

Answer 1

I would add a timeout and a mouseover handler that clears it in the other handler. While the elements could be exactly next to each other visually, adding a small timer is more safe since there might just be a tiny 1px area where the mouseout event fires, causing an ugly flickering.

This also allows a quick mouseshake without flicker.

Something like:

var timer;

img.onmouseout = other.onmouseout = function() {
  timer = setTimeout(closemenu, 100);
}

img.onmouseover = other.onmouseover = function() {
  clearTimeout(timer);
}

function closemenu() {
  // close it
}