Handle missing Web Crypto API in non-HTTPS contexts

Signed-off-by: Shyamsundar Gadde <[email protected]>

Author: ShyamGadde

plugins/optimization-detective/detect.js

@@ -161,6 +161,17 @@ async function getAlreadySubmittedSessionStorageKey(
 	currentUrl,
 	urlMetricGroupStatus
 ) {
+	// Check if crypto.subtle is available.
+	if ( ! window.crypto || ! window.crypto.subtle ) {
+		// eslint-disable-next-line no-console
+		console.warn(
+			'[Optimization Detective] Web Crypto API is not available. This API is only available in secure contexts (HTTPS). Detection cannot proceed. If you are testing locally, ensure you use HTTPS or run on localhost.'
+		);
+		throw new Error(
+			'Web Crypto API is unavailable in this context. Try using HTTPS or localhost.'
+		);
+	}
+
 	const message = [
 		currentETag,
 		currentUrl,
@@ -391,27 +402,33 @@ export default async function detect( {
 		return;
 	}
 
-	// Abort if the client already submitted a URL Metric for this URL and viewport group.
-	const alreadySubmittedSessionStorageKey =
-		await getAlreadySubmittedSessionStorageKey(
-			currentETag,
-			currentUrl,
-			urlMetricGroupStatus
-		);
-	if ( alreadySubmittedSessionStorageKey in sessionStorage ) {
-		const previousVisitTime = parseInt(
-			sessionStorage.getItem( alreadySubmittedSessionStorageKey ),
-			10
-		);
-		if (
-			! isNaN( previousVisitTime ) &&
-			( getCurrentTime() - previousVisitTime ) / 1000 < freshnessTTL
-		) {
-			log(
-				'The current client session already submitted a fresh URL Metric for this URL so a new one will not be collected now.'
+	let alreadySubmittedSessionStorageKey;
+	try {
+		// Abort if the client already submitted a URL Metric for this URL and viewport group.
+		alreadySubmittedSessionStorageKey =
+			await getAlreadySubmittedSessionStorageKey(
+				currentETag,
+				currentUrl,
+				urlMetricGroupStatus
+			);
+		if ( alreadySubmittedSessionStorageKey in sessionStorage ) {
+			const previousVisitTime = parseInt(
+				sessionStorage.getItem( alreadySubmittedSessionStorageKey ),
+				10
 			);
-			return;
+			if (
+				! isNaN( previousVisitTime ) &&
+				( getCurrentTime() - previousVisitTime ) / 1000 < freshnessTTL
+			) {
+				log(
+					'The current client session already submitted a fresh URL Metric for this URL so a new one will not be collected now.'
+				);
+				return;
+			}
 		}
+	} catch ( err ) {
+		warn( 'Unable to create session storage key: ' + err.message );
+		return;
 	}
 
 	// Abort if the viewport aspect ratio is not in a common range.