Replace Rails UJS library (#37031)

app/javascript/mastodon/common.ts

@@ -1,9 +1,5 @@
-import Rails from '@rails/ujs';
+import { setupLinkListeners } from './utils/links';
 
 export function start() {
-  try {
-    Rails.start();
-  } catch {
-    // If called twice
-  }
+  setupLinkListeners();
 }

app/javascript/mastodon/utils/links.ts

@@ -0,0 +1,88 @@
+import { on } from 'delegated-events';
+
+export function setupLinkListeners() {
+  on('click', 'a[data-confirm]', handleConfirmLink);
+
+  // We don't want to target links with data-confirm here, as those are handled already.
+  on('click', 'a[data-method]:not([data-confirm])', handleMethodLink);
+}
+
+function handleConfirmLink(event: MouseEvent) {
+  const anchor = event.currentTarget;
+  if (!(anchor instanceof HTMLAnchorElement)) {
+    return;
+  }
+  const message = anchor.dataset.confirm;
+  if (!message || !window.confirm(message)) {
+    event.preventDefault();
+    return;
+  }
+
+  if (anchor.dataset.method) {
+    handleMethodLink(event);
+  }
+}
+
+function handleMethodLink(event: MouseEvent) {
+  const anchor = event.currentTarget;
+  if (!(anchor instanceof HTMLAnchorElement)) {
+    return;
+  }
+
+  const method = anchor.dataset.method?.toLowerCase();
+  if (!method) {
+    return;
+  }
+  event.preventDefault();
+
+  // Create and submit a form with the specified method.
+  const form = document.createElement('form');
+  form.method = 'post';
+  form.action = anchor.href;
+
+  // Add the hidden _method input to simulate other HTTP methods.
+  const methodInput = document.createElement('input');
+  methodInput.type = 'hidden';
+  methodInput.name = '_method';
+  methodInput.value = method;
+  form.appendChild(methodInput);
+
+  // Add CSRF token if available for same-origin requests.
+  const csrf = getCSRFToken();
+  if (csrf && !isCrossDomain(anchor.href)) {
+    const csrfInput = document.createElement('input');
+    csrfInput.type = 'hidden';
+    csrfInput.name = csrf.param;
+    csrfInput.value = csrf.token;
+    form.appendChild(csrfInput);
+  }
+
+  // The form needs to be in the document to be submitted.
+  form.style.display = 'none';
+  document.body.appendChild(form);
+
+  // We use requestSubmit to ensure any form submit handlers are properly invoked.
+  form.requestSubmit();
+}
+
+function getCSRFToken() {
+  const param = document.querySelector<HTMLMetaElement>(
+    'meta[name="csrf-param"]',
+  );
+  const token = document.querySelector<HTMLMetaElement>(
+    'meta[name="csrf-token"]',
+  );
+  if (param && token) {
+    return { param: param.content, token: token.content };
+  }
+  return null;
+}
+
+function isCrossDomain(href: string) {
+  const link = document.createElement('a');
+  link.href = href;
+  return (
+    link.protocol !== window.location.protocol ||
+    link.host !== window.location.host
+  );
+}