gistfile1.js

function setVisibleTimeout(callback, delay) {
  var id = null,
    t = 0,
    prefix = '';
  'o webkit moz ms'.replace(/\S+/g, function(p) {
    if ((p + 'Hidden') in document) {
      prefix = p;
    }
  });
  function onVisibilityChange(event) {
    var now = +new Date(); // event.timeStamp is buggy in FF 10 (in microseconds)
    if (document[prefix ? prefix + 'Hidden' : 'hidden']) {
      if (id !== null) {
        delay = Math.max(0, delay - Math.max(0, now - t)); // defense from now < t if clock jump occured
        clearTimeout(id);
        id = null;
      }
    } else {
      if (id === null) {
        t = now;
        id = setTimeout(function() {
          id = null;
          document.removeEventListener(prefix + 'visibilitychange', onVisibilityChange, false);
          setTimeout(callback, 0);
        }, delay);
      }
    }
  }
  document.addEventListener(prefix + 'visibilitychange', onVisibilityChange, false);
  onVisibilityChange({timeStamp: +new Date()});
  return (function () {
    document.removeEventListener(prefix + 'visibilitychange', onVisibilityChange, false);
    if (id !== null) {
      clearTimeout(id);
      id = null;
    }
  });
}