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(function () {
function check(url, method, callback) {
const http = new XMLHttpRequest();
http.onreadystatechange = function () {
if (http.readyState === 4 && http.status === 200) {
if (callback) callback(http);
}
};
http.open(method, url);
http.setRequestHeader("Pragma", "no-cache");
http.setRequestHeader("Cache-Control", "no-cache");
http.send();
return http;
}
function update() {
const url = self.location.href.split("#")[0].split("?")[0];
check(url, "HEAD", function (request) {
const local = document.querySelector('meta[name="last-modified"]').content;
const remote = request.getResponseHeader("last-modified") || local;
const modified = Date.parse(document.lastModified) !== Date.parse(remote);
const drift = Date.parse(remote) - Date.parse(local);
if (modified) {
const indicator = document.querySelector("a[data-update]");
check(url, "GET");
indicator.href = url;
indicator.removeAttribute("id");
indicator.dataset.update = "refresh";
self.removeEventListener("blur", update);
console.log("R: " + remote);
console.log("L: " + local);
console.log("D: " + drift);
console.log("M: " + modified);
}
});
}
self.addEventListener("blur", update);
})();
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