Merge pull request #209 from BonnierNews/fix/reduce-scroll-listeners

Fix for scroll listener warnings
BonnierNews · Aug 9, 2024 · 3fbbb10 · 3fbbb10
2 parents bf98ee7 + cd56c79
commit 3fbbb10
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Showing 3 changed files with 14 additions and 3 deletions.
diff --git a/docs/API.md b/docs/API.md
@@ -1,5 +1,5 @@
 <!-- version -->
-# 16.0.0 API Reference
+# 16.0.1 API Reference
 <!-- versionstop -->
 
 <!-- toc -->

diff --git a/lib/IntersectionObserver.js b/lib/IntersectionObserver.js
@@ -15,6 +15,17 @@ module.exports = function fakeIntersectionObserver(browser) {
   const IntersectionObserverEntry = fakeIntersectionObserverEntry(browser);
   browser.window.IntersectionObserverEntry = IntersectionObserverEntry;
 
+  const eventHandlers = [];
+
+  function addEventHandler(handler) {
+    if (eventHandlers.length === 0) {
+      browser.window.addEventListener("scroll", () => {
+        eventHandlers.forEach((fn) => fn());
+      });
+    }
+    eventHandlers.push(handler);
+  }
+
   class IntersectionObserver {
     constructor(viewportUpdate, options) {
       this[kToObserve] = [];
@@ -23,7 +34,7 @@ module.exports = function fakeIntersectionObserver(browser) {
       this[kUpdate] = viewportUpdate;
       this[kRootMargin] = getRootMargin(options);
 
-      browser.window.addEventListener("scroll", () => {
+      addEventHandler(() => {
         const entries = this[kToObserve].map((el) => new IntersectionObserverEntry(el, this[kRootMargin]));
         const changedEntries = entries.filter((entry) => {
           const previous = this[kPrevEntries].find((x) => x.target === entry.target);

diff --git a/package.json b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@expressen/tallahassee",
-  "version": "16.0.0",
+  "version": "16.0.1",
   "description": "Lightweight client testing framework",
   "main": "index.js",
   "license": "BSD-3-Clause",