made the changed files holder sticky

1 files changed, 21 insertions, 0 deletions

diff --git a/app/assets/javascripts/lib/utils/sticky.js b/app/assets/javascripts/lib/utils/sticky.js
new file mode 100644
index 00000000000..f53acaa17b1
--- /dev/null
+++ b/app/assets/javascripts/lib/utils/sticky.js
@@ -0,0 +1,21 @@
+export const isSticky = (el, stickyTop) => {
+  const top = el.getBoundingClientRect().top;
+
+  if (top === stickyTop) {
+    el.classList.add('is-stuck');
+  } else {
+    el.classList.remove('is-stuck');
+  }
+};
+
+export default (el) => {
+  const computedStyle = window.getComputedStyle(el);
+
+  if (!/sticky/.test(computedStyle.position)) return;
+
+  const stickyTop = parseInt(computedStyle.top, 10);
+
+  document.addEventListener('scroll', () => isSticky(el, stickyTop), {
+    passive: true,
+  });
+};