ping command for two-way-delay

js/commands.js

@@ -67,7 +67,8 @@ function cmd_help() {
         "   -exec     Execute arbitrary math and logic equations<br>" +
         "   -nick     Choose your username. Do not use spaces in it<br>" +
         "   -msg      Open a direct chat to the provided user by name<br>" +
-        "   -ls       List all connected users by name and id";
+        "   -ls       List all connected users by name and id<br>" +
+        "   -ping     Ping the host to request two-way-delay";
 }
 
 // Display 'about' message
@@ -206,3 +207,9 @@ function cmd_ls() {
     requestUsernames();
     return null;
 }
+
+// Ping host for two-way-delay
+function cmd_ping() {
+    requestPing();
+    return null;
+}

js/networking.js

@@ -150,3 +150,15 @@ function requestUsernames() {
         outputText({ output });
     });
 }
+
+// Ping host for two-way-delay
+function requestPing() {
+    const startTime = new Date();
+    fetch('/ping').then(res => {
+        if (res.status !== 200)
+            return;
+        const diff = new Date() - startTime;
+        const output = `Host responded after ${diff}ms.`;
+        outputText({output})
+    });
+}