1 files changed, 33 insertions, 21 deletions
diff --git a/content.js b/content.js
index 153f5a5..1df4deb 100644
--- a/content.js
+++ b/content.js
@@ -1,23 +1,35 @@
-// ... / NixOS / nixpkgs / pull / <number> / ...
-const number = new URL(window.location.href).pathname.split('/')[4]
+function sprongulate() {
+  // Since GitHub is an SPA, we can't limit ourselves to only loading on
+  // specifically nixpkgs PRs, as synthetic browser navigation doesn't
+  // trigger content script loading. Thus, we have to load on all pages,
+  // and ensure we're on a nixpkgs PR before running.
+  const [, NixOS, nixpkgs, pull, number] = new URL(window.location.href).pathname.split('/')
+  if (NixOS !== 'NixOS' || nixpkgs !== 'nixpkgs' || pull !== 'pull') return
 
-// There are (at the time of writing) two contexts in which the PR
-// number is visible:
-//
-//   1. in the header (following the PR title)
-//   2. sufficiently far down that the header is no longer visible (at
-//   which point the header shrinks and affixes itself to the top of the
-//   page)
-//
-// These are actually two distinct elements, the visibility of which
-// are dependent on your scroll position. They also have completely
-// different (and nondescript) CSS selectors, so instead of looking for
-// them directly, we locate the immediately preceding PR title elements
-// (which do have a common CSS selector), and grab their next sibling.
-for (let node of document.querySelectorAll('.js-issue-title')) {
-  node = node.nextElementSibling
-  const a = document.createElement('a')
-  a.setAttribute('href', `https://nixpk.gs/pr-tracker.html?pr=${number}`)
-  node.replaceWith(a)
-  a.appendChild(node)
+  // There are (at the time of writing) two contexts in which the PR
+  // number is visible:
+  //
+  //   1. in the header (following the PR title)
+  //   2. sufficiently far down that the header is no longer visible (at
+  //   which point the header shrinks and affixes itself to the top of
+  //   the page)
+  //
+  // These are actually two distinct elements, the visibility of which
+  // are dependent on your scroll position. They also have completely
+  // different (and nondescript) CSS selectors, so instead of looking
+  // for them directly, we locate the immediately preceding PR title
+  // elements (which *do* have a common CSS selector), to find them.
+  for (let node of document.querySelectorAll('.js-issue-title')) {
+    node = node.nextElementSibling
+    const a = document.createElement('a')
+    a.setAttribute('href', `https://nixpk.gs/pr-tracker.html?pr=${number}`)
+    node.replaceWith(a)
+    a.appendChild(node)
+  }
 }
+
+// Once on first page load...
+sprongulate()
+
+// ...and once every time there is new page content.
+document.addEventListener('pjax:end', sprongulate)