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(function () {
function fetch(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];
const indicator = document.querySelector("a[data-update]");
if (indicator.dataset.update === "refresh" || indicator === null) return;
const anchor = indicator.cloneNode();
fetch(url, "HEAD", function (request) {
const local = document.querySelector('meta[name="last-modified"]').content || document.lastModified;
const remote = request.getResponseHeader("last-modified") || document.lastModified;
const modified = Date.parse(remote) > Date.parse(local);
const drift = Date.parse(remote) - Date.parse(local);
if (drift < 3000) return;
function reset() {
indicator.href = anchor.href;
indicator.setAttribute("id", anchor.id);
indicator.dataset.update = anchor.dataset.update;
}
if (remote && modified) {
fetch(url, "GET");
indicator.href = url;
indicator.removeAttribute("id");
indicator.dataset.update = "refresh";
console.log("INFO: R: " + remote);
console.log("INFO: L: " + local);
console.log("INFO: D: " + drift);
console.log("INFO: M: " + modified);
}
});
}
let scrolled;
let delay = 1000;
let delayed = 0;
self.addEventListener("scroll", function () {
if (scrolled) clearTimeout(scrolled);
scrolled = setTimeout(function () { update(); delay = delay + delayed; delayed = delay - delayed; }, delay);
});
["focus", "load", "URLChangedCustomEvent"].forEach(function (event) {
self.addEventListener(event, function () { update(); });
});
})();
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