ui: add experimental speculation rules

packages/ui-default/pages/contest.page.ts

@@ -1,7 +1,7 @@
 import { formatSeconds } from '@hydrooj/utils/lib/common';
 import NProgress from 'nprogress';
 import { NamedPage } from 'vj/misc/Page';
-import { tpl } from 'vj/utils';
+import { addSpeculationRules, tpl } from 'vj/utils';
 
 const contestTimer = $(tpl`<pre class="contest-timer" style="display:none"></pre>`);
 contestTimer.appendTo(document.body);
@@ -21,4 +21,15 @@ export default new NamedPage(['contest_detail', 'contest_problemlist', 'contest_
   NProgress.start();
   updateProgress();
   setInterval(updateProgress, 1000);
+
+  addSpeculationRules({
+    prerender: [{
+      'where': {
+        'or': [
+          { 'href_matches': '/p/*' },
+          { 'href_matches': '/d/*/p/*' },
+        ],
+      },
+    }],
+  });
 });

packages/ui-default/pages/problem_main.page.ts

@@ -9,7 +9,7 @@ import Notification from 'vj/components/notification';
 import { downloadProblemSet } from 'vj/components/zipDownloader';
 import { NamedPage } from 'vj/misc/Page';
 import {
-  delay, i18n, pjax, request, tpl,
+  addSpeculationRules, delay, i18n, pjax, request, tpl,
 } from 'vj/utils';
 
 const list = [];
@@ -343,6 +343,17 @@ const page = new NamedPage(['problem_main'], () => {
   });
   $(document).on('vjContentNew', (e) => processElement(e.target));
   processElement(document);
+
+  addSpeculationRules({
+    prerender: [{
+      'where': {
+        'or': [
+          { 'href_matches': '/p/*' },
+          { 'href_matches': '/d/*/p/*' },
+        ],
+      },
+    }],
+  });
 });
 
 export default page;

packages/ui-default/utils/base.ts

@@ -2,7 +2,6 @@ import $ from 'jquery';
 import _ from 'lodash';
 import React from 'react';
 import ReactDOM from 'react-dom/client';
-import DOMServer from 'react-dom/server';
 
 export function substitute(str: string, obj: any) {
   return str.replace(/\{([^{}]+)\}/g, (match, key) => {
@@ -38,12 +37,13 @@ export function tpl<T extends boolean = false>(node: React.ReactNode, reactive?:
 export function tpl(pieces: TemplateStringsArray, ...substitutions: Substitution[]): string;
 export function tpl(pieces: TemplateStringsArray | React.ReactNode, ...substitutions: Substitution[] | boolean[]) {
   if (React.isValidElement(pieces)) {
-    if (substitutions[0]) {
     const div = document.createElement('div');
-      ReactDOM.createRoot(div).render(pieces);
+    const root = ReactDOM.createRoot(div);
-      return div;
+    root.render(pieces);
-    }
+    if (substitutions[0]) return div;
-    return DOMServer.renderToStaticMarkup(pieces);
+    const html = div.innerHTML;
+    root.unmount();
+    return html;
   }
   let result = pieces[0];
   for (let i = 0; i < substitutions.length; ++i) {
@@ -81,6 +81,15 @@ export const zIndexManager = {
   },
 };
 
+export function addSpeculationRules(rules) {
+  if (HTMLScriptElement.supports?.('speculationrules')) {
+    const specScript = document.createElement('script');
+    specScript.type = 'speculationrules';
+    specScript.textContent = JSON.stringify(rules);
+    document.body.append(specScript);
+  }
+}
+
 export const request = {
   ajax(options: Record<string, any>) {
     const stack = new Error().stack;