Merge pull request #1712 from WordPress/fix/od-abort-url-metrics-submission-on-viewport-size-change

Prevent submitting URL Metric if viewport size changed

Author: westonruter

plugins/optimization-detective/detect.js

@@ -325,6 +325,16 @@ export default async function detect( {
 		return;
 	}
 
+	// Keep track of whether the window resized. If it resized, we abort sending the URLMetric.
+	let didWindowResize = false;
+	window.addEventListener(
+		'resize',
+		() => {
+			didWindowResize = true;
+		},
+		{ once: true }
+	);
+
 	// TODO: Does this make sense here?
 	// Prevent detection when page is not scrolled to the initial viewport.
 	if ( doc.documentElement.scrollTop > 0 ) {
@@ -507,6 +517,17 @@ export default async function detect( {
 		);
 	} );
 
+	// Only proceed with submitting the URL Metric if viewport stayed the same size. Changing the viewport size (e.g. due
+	// to resizing a window or changing the orientation of a device) will result in unexpected metrics being collected.
+	if ( didWindowResize ) {
+		if ( isDebug ) {
+			log(
+				'Aborting URL Metric collection due to viewport size change.'
+			);
+		}
+		return;
+	}
+
 	if ( extensions.size > 0 ) {
 		for ( const [
 			extensionModuleUrl,