Determine the user's online status onbeforeunload event_javascript skills

Needless to say, getting the user's login status is a bit problematic. It is a bit problematic to judge whether the user has left. If the user triggers the exit event and leaves according to the designer's regulations, it will not be difficult. However, there are many ways for users to leave. How to determine the user's departure? What about the immediate decision to leave when leaving illegally? The most common illegal exit is to close the browser.

Copy code The code is as follows:

<script> <BR>window.onbeforeunload = function() { <BR>if (window.event.clientX>document.body.clientWidth&&event.clientY<0||event.altKey) <BR>{ <BR>alert("Browser close"); <BR>} <BR>else <BR>{ <BR>alert("Refresh or jump to other pages"); <BR>} <BR>} <BR>&lt ;/script> <BR> <BR></script>

The above is a fragment. BODY's UNLOAD and onbeforeunload events will be triggered when the browser clears the loaded information, which means that the page is It will be triggered when sending back, redirecting or being closed. By adding JAVASCRIPT processing to this event, you can illegally close the browser and count the number of people online in real time.

But there is a problem, how to determine whether the user is closing, refreshing, posting, or redirecting?

window.event.clientX and window.event.clientY will capture the desktop coordinates of the mouse relative to the window when the current event occurs. Normally, IE's close button will be in the upper right part of the page, so when you click Close The Y coordinate of the mouse coordinates must be less than 0. In addition, the coordinate value in the X direction of the mouse coordinates will be greater than the width of the form. Therefore, from these two conditions, it can be judged whether the mouse clicks on the onbeforeload event triggered by the close button.
Another closing method is ALT F4. You can use event.altKey to determine whether the ALT key was pressed when the event occurred. This way you can determine whether it is time to ALT F4 to close the window.

However, there is also a problem. When using some special left themes, the coordinate value that can be triggered by the close button is not necessarily smaller than the width of the form. Therefore, window.event.clientX>document.body in the above example The .clientWidth condition is optional.