Tu masz skrypt:
var vis = (function(){
var stateKey, eventKey, keys = {
hidden: "visibilitychange",
webkitHidden: "webkitvisibilitychange",
mozHidden: "mozvisibilitychange",
msHidden: "msvisibilitychange"
};
for (stateKey in keys) {
// Google Chrome: if ("webkitHidden" in document) {
if (stateKey in document) {
// Google Chrome: eventKey = keys["webkitHidden"];
// eventKey = "webkitvisibilitychange";
eventKey = keys[stateKey];
break;
}
}
return function(c) {
// Google Chrome: if (c) document.addEventListener("webkitvisibilitychange", c);
if (c) document.addEventListener(eventKey, c);
// Google Chrome: return !document["webkitHidden"];
return !document[stateKey];
}
})();
P.S. Mam nadzieję, że teraz to zrozumiesz