1 files changed, 22 insertions, 0 deletions
diff --git a/cli/js/performance.ts b/cli/js/performance.ts
new file mode 100644
index 000000000..6ea8e56e1
--- /dev/null
+++ b/cli/js/performance.ts
@@ -0,0 +1,22 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+import * as dispatch from "./dispatch.ts";
+import { sendSync } from "./dispatch_json.ts";
+
+interface NowResponse {
+  seconds: number;
+  subsecNanos: number;
+}
+
+export class Performance {
+  /** Returns a current time from Deno's start in milliseconds.
+   *
+   * Use the flag --allow-hrtime return a precise value.
+   *
+   *       const t = performance.now();
+   *       console.log(`${t} ms since start!`);
+   */
+  now(): number {
+    const res = sendSync(dispatch.OP_NOW) as NowResponse;
+    return res.seconds * 1e3 + res.subsecNanos / 1e6;
+  }
+}