Implemented Stopwatch to simplify measurements

src/utils/stopwatch.ts

@@ -0,0 +1,68 @@
+interface StartCallback {
+    (currentDate: Date, stopwatch: Stopwatch): void;
+}
+
+interface StopCallback {
+    (elapsedMilliseconds: number, currentDate: Date, stopwatch: Stopwatch): void;
+}
+
+export default class Stopwatch {
+    #initialDate = 0;
+    #isRunning = false;
+    #elapsedMilliseconds = 0;
+    #onStart: StartCallback = null;
+    #onStop: StopCallback = null;
+
+    public constructor(onStart?: StartCallback, onStop?: StopCallback) {
+        this.#onStart = onStart;
+        this.#onStop = onStop;
+    }
+
+    public get elapsedMilliseconds(): number {
+        return this.#isRunning
+            ? (this.#elapsedMilliseconds + new Date().valueOf() - this.#initialDate)
+            : this.#elapsedMilliseconds;
+    }
+
+    public get isRunning(): boolean {
+        return this.#isRunning;
+    }
+
+    public start(): boolean {
+        if (!this.#isRunning) {
+            const currentDate = new Date();
+            this.#initialDate = currentDate.valueOf();
+            this.#isRunning = true;
+            this.#onStart?.(currentDate, this);
+            return true;
+        }
+        return false;
+    }
+
+    public stop(): boolean {
+        if (this.#isRunning) {
+            const currentDate = new Date();
+            this.#elapsedMilliseconds += currentDate.valueOf() - this.#initialDate;
+            this.#isRunning = false;
+            this.#onStop?.(this.#elapsedMilliseconds, currentDate, this);
+            return true;
+        }
+        return false;
+    }
+
+    public reset(): void {
+        this.stop();
+        this.#elapsedMilliseconds = 0;
+    }
+
+    public restart(): void {
+        this.reset();
+        this.start();
+    }
+
+    public static startNew(onStart?: StartCallback, onStop?: StopCallback): Stopwatch {
+        const stopwatch = new Stopwatch(onStart, onStop);
+        stopwatch.start();
+        return stopwatch;
+    }
+}

test/stopwatch.test.ts

@@ -0,0 +1,59 @@
+import { describe, test, expect } from "@jest/globals";
+import sleep from "../src/utils/sleep";
+import Stopwatch from "../src/utils/stopwatch";
+
+describe("Stopwatch", () => {
+    test("base functionality of Stopwatch works", async () => {
+        const stopwatch = new Stopwatch();
+        expect(stopwatch.isRunning).toBe(false);
+        expect(stopwatch.elapsedMilliseconds).toBe(0);
+        expect(stopwatch.start()).toBe(true);
+        await sleep(100);
+        expect(stopwatch.start()).toBe(false);
+        expect(stopwatch.stop()).toBe(true);
+        expect(stopwatch.stop()).toBe(false);
+        expect(stopwatch.elapsedMilliseconds).toBeGreaterThan(50);
+        expect(stopwatch.elapsedMilliseconds).toBeLessThan(200);
+        stopwatch.reset();
+        expect(stopwatch.elapsedMilliseconds).toBe(0);
+    });
+
+    test("Stopwatch executes callbacks on start and end", async () => {
+        let started = 0;
+        let stopped = 0;
+        let ms = 0;
+
+        const stopwatch = new Stopwatch(() => ++started, elapsedMilliseconds => {
+            ++stopped;
+            ms = elapsedMilliseconds;
+        });
+
+        expect(stopwatch.isRunning).toBe(false);
+        expect(stopwatch.elapsedMilliseconds).toBe(0);
+
+        expect(stopwatch.start()).toBe(true);
+        expect(started).toBe(1);
+        expect(stopped).toBe(0);
+
+        await sleep(100);
+
+        expect(stopwatch.start()).toBe(false);
+        expect(started).toBe(1);
+        expect(stopped).toBe(0);
+
+        expect(stopwatch.stop()).toBe(true);
+        expect(started).toBe(1);
+        expect(stopped).toBe(1);
+
+        expect(stopwatch.stop()).toBe(false);
+        expect(started).toBe(1);
+        expect(stopped).toBe(1);
+
+        expect(stopwatch.elapsedMilliseconds).toBeGreaterThan(50);
+        expect(stopwatch.elapsedMilliseconds).toBeLessThan(200);
+        expect(stopwatch.elapsedMilliseconds).toBe(ms);
+
+        stopwatch.reset();
+        expect(stopwatch.elapsedMilliseconds).toBe(0);
+    });
+});