add user agent string and also dont do HEAD requst for initial requst

index.js

@@ -41,13 +41,17 @@ function sleep(ms) {
 	let resps = [];
 	let firstRemoteTime = undefined;
 	let foundChange = undefined;
-
-	await conn.request({
-		method: "HEAD",
+	let reqtempl = {
+		method: "OPTIONS",
 		path: url.pathname + url.search,
+		headers: {
+			"user-agent": "webtimediff"
+		},
 		blocking: false,
 		idempotent: true,
-	});
+	}
+
+	await conn.request(reqtempl);
 
 	for (let i = 0; (!foundChange) && i < end; i += step) {
 		if (errors.length > 0)
@@ -55,12 +59,7 @@ function sleep(ms) {
 
 		let date = new Date();
 		let ii=i;
-		let res = conn.request({
-			method: "OPTIONS",
-			path: url.pathname + url.search,
-			blocking: false,
-			idempotent: true,
-		}).then(e => (
+		let res = conn.request(reqtempl).then(e => (
 			e.date = new Date(e.headers.date),
 			firstRemoteTime = firstRemoteTime ?? e.date,
 			e.madeAt = date,