/*
* fix the 'lastModified' difference between major browsers
*/
var lastModified = function (defer) {
// when server does not send Last-Modified Header opera provide a minimum datetime value.
var time = new Date(document.lastModified);
if (time.getTime() === 0) { return null; }
// assume that this script will be executed in 30 seconds after the clien page loaded.
var now = new Date(), deferTicks = (defer || 30) * 1000;
if (browser.chrome || browser.safari) {
// chrome and safari use a LocalTime type
var offset = -now.getTimezoneOffset(); // unit of minute
time = new Date(time.getTime() + (offset * 60 * 1000));
}
if (now - time < deferTicks) { return null; }
// ret
return time.getTime();
} ();
参考文档:
https://developer.mozilla.org/en/DOM/document.lastModified