Working example with start cancel

src/extension.ts

@@ -1,11 +1,53 @@
 import * as vscode from 'vscode';
 
-export function activate(context: vscode.ExtensionContext) {
-  const disposable = vscode.commands.registerCommand('speed-code.startSpeedRun', () => {
-    vscode.window.showInformationMessage('Hello World from My Extension!');
-  });
+let resetTimer = () => {}
 
-  context.subscriptions.push(disposable);
+export function activate(context: vscode.ExtensionContext) {
+  const statusBarItem = vscode.window.createStatusBarItem(vscode.StatusBarAlignment.Left, 100);
+  statusBarItem.tooltip = 'Speedrun timer';
+  statusBarItem.text = "No active Speedrun";
+  statusBarItem.show();
+
+  let timer: undefined | NodeJS.Timeout;
+
+  resetTimer = () => {
+    if (timer) {
+      clearInterval(timer);
+    }
+    statusBarItem.text = "No active Speedrun";
+  };
+
+  resetTimer();
+
+  context.subscriptions.push(vscode.commands.registerCommand('speed-code.startSpeedRun', () => {
+    const startTime = Date.now();
+    timer = setInterval(() => {
+      const currentTime = Date.now();
+      const timeSeconds = (currentTime - startTime) / 1000;
+      if (timeSeconds > 86400) {
+        const days = Math.floor(timeSeconds / 86400);
+        const hours = Math.floor(timeSeconds / 3600);
+        const minutes = Math.floor(timeSeconds / 60);
+        statusBarItem.text = `${days}:${hours - (days * 24)}:${minutes - (hours * 60)}:${(timeSeconds - (minutes * 60)).toFixed(3)}`;
+      } else if (timeSeconds >= 3600) {
+        const hours = Math.floor(timeSeconds / 3600);
+        const minutes = Math.floor(timeSeconds / 60);
+        statusBarItem.text = `${hours}:${minutes - (hours * 60)}:${(timeSeconds - (minutes * 60)).toFixed(3)}`;
+      } else if (timeSeconds >= 60) {
+        const minutes = Math.floor(timeSeconds / 60);
+        statusBarItem.text = `${minutes}:${(timeSeconds - (minutes * 60)).toFixed(3)}`;
+      } else {
+        statusBarItem.text = `${timeSeconds}`;
+      }
+      statusBarItem.color = '#fff';
+    }, 10);
+
+    vscode.window.showInformationMessage('Speedrun Started!');
+  }), statusBarItem);
+
+  context.subscriptions.push(vscode.commands.registerCommand('speed-code.cancelSpeedRun', resetTimer), statusBarItem);
 }
 
-export function deactivate() {}
+export function deactivate() {
+  resetTimer();
+}