arimelody.me/public/script/swap.js

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const swap_event = new Event("swap");
let caches = {};
async function cached_fetch(url) {
let cached = caches[url];
const res = cached === undefined ? await fetch(url) : await fetch(url, {
headers: {
"If-Modified-Since": cached.last_modified
}
});
if (res.status === 304 && cached !== undefined) {
return cached.content;
}
if (res.status !== 200) return;
if (!res.headers.get("content-type").startsWith("text/html")) return;
const text = await res.text();
if (res.headers.get("last-modified")) {
caches[url] = {
content: text,
last_modified: res.headers.get("last-modified")
}
}
return text;
}
async function swap(url, stateful) {
if (typeof url !== 'string') return;
const segments = window.location.href.split("/");
if (url.startsWith(window.location.origin) && segments[segments.length - 1].includes("#")) {
window.location.href = url;
return;
}
if (stateful && window.location.href.endsWith(url)) return;
const text = await cached_fetch(url);
const content = new DOMParser().parseFromString(text, "text/html");
const stylesheets = [...content.querySelectorAll("link[rel='stylesheet']")];
// swap title
document.title = content.title;
// swap body html
document.body.innerHTML = content.body.innerHTML;
// swap stylesheets
const old_sheets = document.head.querySelectorAll("link[rel='stylesheet']");
stylesheets.forEach(stylesheet => {
let exists = false;
old_sheets.forEach(old_sheet => {
if (old_sheet.href === stylesheet.href) exists = true;
});
if (!exists) document.head.appendChild(stylesheet);
});
old_sheets.forEach(old_sheet => {
let exists = false;
stylesheets.forEach(stylesheet => {
if (stylesheet.href === old_sheet.href) exists = true;
});
if (!exists) old_sheet.remove();
});
// push history
if (stateful) history.pushState(url, "", url);
bind(document.body);
}
function bind(content) {
if (typeof content !== 'object' || content.nodeType !== Node.ELEMENT_NODE) return;
content.querySelectorAll("[swap-url]").forEach(element => {
const href = element.attributes.getNamedItem('swap-url').value;
element.addEventListener("click", event => {
event.preventDefault();
swap(href, true);
});
[...element.querySelectorAll("a[href], [swap-url]")].forEach(element => {
if (element.href) {
if (!element.href.endsWith(href)) return;
element.attributes.removeNamedItem("href");
}
const swap_url = element.attributes.getNamedItem("swap-url");
if (swap_url) {
if (!swap_url.endsWith(href)) return;
element.attributes.removeNamedItem("swap-url");
}
});
});
content.querySelectorAll("a[href]:not([swap-url])").forEach(element => {
if (element.href.includes("#")) return;
if (!element.href.startsWith(window.location.origin)) return;
const href = element.href.substring(window.location.origin.length);
if (href.includes(".")) return;
element.addEventListener("click", event => {
event.preventDefault();
swap(element.href, true);
});
});
document.dispatchEvent(swap_event);
}
window.addEventListener("popstate", event => {
swap(event.state, false);
});
document.addEventListener("DOMContentLoaded", () => {
bind(document.body);
});