From: Marius Gavrilescu <marius@ieval.ro>
Date: Fri, 17 Apr 2015 21:09:33 +0000 (+0300)
Subject: Use server time in 90-timers.js for more accurate timers
X-Git-Url: http://git.ieval.ro/?p=plack-app-gruntmaster.git;a=commitdiff_plain;h=bbacb12cf514480d7a34b3c39fdebc7ffb5a7315

Use server time in 90-timers.js for more accurate timers
---

diff --git a/js/90-timers.js b/js/90-timers.js
index d439299..e03ae08 100644
--- a/js/90-timers.js
+++ b/js/90-timers.js
@@ -1,8 +1,10 @@
+let offset = 0;
+
 function update_timer(timer){
 	var start = parseInt(timer.dataset.start);
 	var stop  = parseInt(timer.dataset.stop);
 	var value = parseInt(timer.dataset.value);
-	var now   = Math.floor(Date.now() / 1000);
+	var now   = Math.floor(Date.now() / 1000) + offset;
 
 	var left = stop - now;
 	var total = stop - start;
@@ -23,7 +25,17 @@ function update_timer(timer){
 	}
 }
 
-$(() => $('.timer').each(item => {
-	update_timer(item);
-	setInterval(() => update_timer(item), 1000);
-}));
+$(() => {
+	$('.timer').each(item => {
+		update_timer(item);
+		setInterval(() => update_timer(item), 1000);
+	});
+	let xhr = new XMLHttpRequest();
+	xhr.open('HEAD', '/');
+	xhr.onload = () => {
+		let srvtime = Date.parse(xhr.getResponseHeader('Date'));
+		offset = Math.ceil((srvtime - Date.now()) / 1000);
+		console.log("Offset from server: " + offset);
+	};
+	xhr.send();
+});