🐛 [RUMF-1344] scroll positions: remove fallback for null scrollingEle…

…ment (#1694)
DataDog · Aug 17, 2022 · c727be2 · c727be2
1 parent 33f310f
commit c727be2
Showing 1 changed file with 8 additions and 35 deletions.
diff --git a/packages/rum/src/domain/record/elementsScrollPositions.ts b/packages/rum/src/domain/record/elementsScrollPositions.ts
@@ -1,27 +1,19 @@
-import { addTelemetryDebug } from '@datadog/browser-core'
-
 export type ElementsScrollPositions = ReturnType<typeof createElementsScrollPositions>
 export type ScrollPositions = { scrollLeft: number; scrollTop: number }
 
 export function createElementsScrollPositions() {
   const scrollPositionsByElement = new WeakMap<Element, ScrollPositions>()
-  let documentScrollingElement: Element | null
   return {
     set(element: Element | Document, scrollPositions: ScrollPositions) {
-      if (element === document && !documentScrollingElement) {
-        documentScrollingElement = tryToFindScrollingElement(scrollPositions)
-        if (!documentScrollingElement) {
-          return
-        }
-      }
-      try {
-        scrollPositionsByElement.set(
-          element === document ? documentScrollingElement! : (element as Element),
-          scrollPositions
-        )
-      } catch (e) {
-        addTelemetryDebug(`invalid element: ${String(element)}`)
+      if (element === document && !document.scrollingElement) {
+        // cf https://drafts.csswg.org/cssom-view/#dom-document-scrollingelement,
+        // in some cases scrolling elements can not be defined, we don't support those for now
+        return
       }
+      scrollPositionsByElement.set(
+        element === document ? document.scrollingElement! : (element as Element),
+        scrollPositions
+      )
     },
     get(element: Element) {
       return scrollPositionsByElement.get(element)
@@ -31,22 +23,3 @@ export function createElementsScrollPositions() {
     },
   }
 }
-
-function tryToFindScrollingElement(scrollPositions: ScrollPositions) {
-  if (document.scrollingElement) {
-    return document.scrollingElement
-  }
-  addTelemetryDebug('null document scrolling element')
-  if (scrollPositions.scrollLeft === 0 && scrollPositions.scrollTop === 0) {
-    addTelemetryDebug('Unable to find scrolling element for scroll (0,0)')
-    return null
-  }
-  if (
-    Math.round(document.documentElement.scrollLeft) === scrollPositions.scrollLeft &&
-    Math.round(document.documentElement.scrollTop) === scrollPositions.scrollTop
-  ) {
-    return document.documentElement
-  }
-  addTelemetryDebug('Unable to find scrolling element')
-  return null
-}