Stopwatch in JavaScript

1// Method 1: Simple stopwatch
2class Stopwatch {
3    constructor() {
4        this.startTime = null;
5        this.elapsedTime = 0;
6        this.isRunning = false;
7        this.interval = null;
8    }
9    
10    start() {
11        if (!this.isRunning) {
12            this.startTime = Date.now() - this.elapsedTime;
13            this.isRunning = true;
14            this.interval = setInterval(() => {
15                this.elapsedTime = Date.now() - this.startTime;
16                this.onUpdate();
17            }, 10); // Update every 10ms
18        }
19    }
20    
21    stop() {
22        if (this.isRunning) {
23            clearInterval(this.interval);
24            this.isRunning = false;
25        }
26    }
27    
28    reset() {
29        this.stop();
30        this.elapsedTime = 0;
31        this.onUpdate();
32    }
33    
34    onUpdate() {
35        const time = this.formatTime(this.elapsedTime);
36        console.log(time);
37    }
38    
39    formatTime(milliseconds) {
40        const totalSeconds = Math.floor(milliseconds / 1000);
41        const minutes = Math.floor(totalSeconds / 60);
42        const seconds = totalSeconds % 60;
43        const ms = Math.floor((milliseconds % 1000) / 10);
44        
45        return `${String(minutes).padStart(2, '0')}:${String(seconds).padStart(2, '0')}.${String(ms).padStart(2, '0')}`;
46    }
47    
48    getTime() {
49        return this.elapsedTime;
50    }
51}
52
53const stopwatch = new Stopwatch();
54stopwatch.start();
55
56// Method 2: Stopwatch with laps
57class StopwatchWithLaps extends Stopwatch {
58    constructor() {
59        super();
60        this.laps = [];
61    }
62    
63    lap() {
64        if (this.isRunning) {
65            const lapTime = this.elapsedTime - (this.laps.length > 0 ? 
66                this.laps.reduce((sum, lap) => sum + lap, 0) : 0);
67            this.laps.push(lapTime);
68            console.log(`Lap ${this.laps.length}: ${this.formatTime(lapTime)}`);
69            return lapTime;
70        }
71    }
72    
73    getLaps() {
74        return this.laps;
75    }
76    
77    reset() {
78        super.reset();
79        this.laps = [];
80    }
81}
82
83const lapStopwatch = new StopwatchWithLaps();
84lapStopwatch.start();
85// lapStopwatch.lap(); // Record lap
86
87// Method 3: Multiple stopwatches
88class MultiStopwatch {
89    constructor() {
90        this.stopwatches = new Map();
91    }
92    
93    create(id) {
94        const sw = new Stopwatch();
95        this.stopwatches.set(id, sw);
96        return sw;
97    }
98    
99    get(id) {
100        return this.stopwatches.get(id);
101    }
102    
103    remove(id) {
104        const sw = this.stopwatches.get(id);
105        if (sw) sw.stop();
106        this.stopwatches.delete(id);
107    }
108}
109
110const multi = new MultiStopwatch();
111const sw1 = multi.create('timer1');
112sw1.start();