⚡️ start mutation observer only when needed

DataDog · May 19, 2021 · 0841bdd · 0841bdd
1 parent 8ce7325
commit 0841bdd
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Showing 3 changed files with 5 additions and 6 deletions.
diff --git a/packages/rum-core/src/boot/rum.ts b/packages/rum-core/src/boot/rum.ts
@@ -46,7 +46,6 @@ export function startRum(userConfiguration: RumUserConfiguration, getCommonConte
   startRequestCollection(lifeCycle, configuration)
   startPerformanceCollection(lifeCycle, configuration)
   startDOMMutationCollection(lifeCycle)
-
   const internalContext = startInternalContext(userConfiguration.applicationId, session, parentContexts)
 
   return {

diff --git a/packages/rum-core/src/browser/domMutationCollection.ts b/packages/rum-core/src/browser/domMutationCollection.ts
@@ -41,11 +41,7 @@ export function startDOMMutationCollection(lifeCycle: LifeCycle) {
   let observer: MutationObserver | undefined
   const MutationObserver = getMutationObserverConstructor()
   if (MutationObserver) {
-    observer = new MutationObserver(
-      monitor(() => {
-        lifeCycle.notify(LifeCycleEventType.DOM_MUTATED)
-      })
-    )
+    observer = new MutationObserver(monitor(() => lifeCycle.notify(LifeCycleEventType.DOM_MUTATED)))
 
     observer.observe(document.documentElement, {
       attributes: true,

diff --git a/packages/rum-core/src/domain/trackPageActivities.ts b/packages/rum-core/src/domain/trackPageActivities.ts
@@ -1,4 +1,5 @@
 import { monitor, Observable, TimeStamp, timeStampNow } from '@datadog/browser-core'
+import { startDOMMutationCollection } from '../browser/domMutationCollection'
 import { LifeCycle, LifeCycleEventType, Subscription } from './lifeCycle'
 
 // Delay to wait for a page activity to validate the tracking process
@@ -66,6 +67,8 @@ export function trackPageActivities(
   let firstRequestIndex: undefined | number
   let pendingRequestsCount = 0
 
+  const DOMMutationCollection = startDOMMutationCollection(lifeCycle)
+
   subscriptions.push(lifeCycle.subscribe(LifeCycleEventType.DOM_MUTATED, () => notifyPageActivity()))
 
   subscriptions.push(
@@ -108,6 +111,7 @@ export function trackPageActivities(
     observable,
     stop: () => {
       subscriptions.forEach((s) => s.unsubscribe())
+      DOMMutationCollection.stop()
     },
   }
 }