Still Alive

Do something periodically. If the user appears to be absent, go to sleep and stop doing the thing until they return.

Monitor user activity. While the user is active, execute the defined function periodically on the defined time interval. When the user does not interact with the page in the defined way for a specified amount of time, go to sleep. While asleep, the specified function is not called. Upon waking, the specified function is executed immediately and the periodic execution of the function resumes.

Syntax

$.stillAlive(callback [, interval] [, immediately] [, wakeEvents])
$.stillAlive(callback [,options])

callback

callback (required) is the function which will be called periodically.

interval

interval (optional) is the number of milliseconds to elapse between executions of callback. The default value is 60000 (60 seconds).

immediately

immediately (optional) must evaluate to a boolean. The default value is true.

• When immediately is true, callback is executed immediately after $.stillAlive() is called.
• When immediately is false, callback executes for the first time only after interval milliseconds have elapsed.

In both cases, callback is called immediately upon transitioning from a sleep to wake state.

wakeEvents

wakeEvents (optional) is a string containing all of the events which will set an "awake" status and allow callback to be executed. The default value is "mousemove mousedown mouseup keydown keyup".

options

options (optional) is a list of any combination of the optional arguments in object literal notation. Here is an example of explicitly calling $.stillAlive() on a function called "glados" (defined elsewhere) with default options in object literal notation:

$.stillAlive(glados, {
  interval: 60000,
  immediately: true,
  wakeEvents: 'mousemove mousedown mouseup keydown keyup'
});

Examples

Say I have a function called update defined elsewhere. I want update to be called every 60 seconds unless the user doesn't seem to be around. I'd just

$.stillAlive(update);

How about every 15 seconds?

$.stillAlive(update, 15);

Let's toggle a class of some elements every 90 seconds, but only if the user has clicked or typed something, and don't run it immediately after being set.

$.stillAlive(function() {
  $('.togglies').toggleClass('toggly');
}, 90, false, 'click keyup');

The previous code could also be more explicitly called thusly:

$.stillAlive(function() {
  $('.togglies').toggleClass('toggly');
}, {
  interval: 90,
  immediately: false,
  wakeEvents: 'click keyup'
});

And for good measure, here's a call using object literal notation, but only adjusting the interval:

$.stillAlive(update, { interval: 5 });

Copyright and License

Copyright © 2011, Justin Force

Licensed under the BSD 3-Clause License