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HTML

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CSS

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CSS Base

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HTML 

              
                # SpeedClock class

## constructor

```js
const clock = new SpeedClock();

// or chain it:
const runningClock = new SpeedClock().start();
```

## start

Starts the clock. 

<strong>returns:</strong> instance (so it is chainable)

```js
const speedFactor = 1; /* default value */
clock.start(speedFactor);

// if no speedFactor is specified, 
// it takes the current speed factor
// the speedFactor is initially 1
clock.start();
```

## stop

Stops the clock

<strong>returns:</strong> instance

```js
clock.stop();
```

## reset

Resets the clock to zero. Doesn't change the speedFactor.

<strong>returns:</strong> instance

```js
clock.reset();
```

<strong>returns:</strong> instance

## running

Returns whether the clock is running

<strong>type:</strong> boolean, readonly

```
const running = clock.running;
```

## elapsedTime 

<strong>type:</strong> number, readonly

```
const elapsed = clock.elapsedTime
```

## speedFactor 

<strong>type:</strong> number

Get or set the speed factor, also while the clock is running.

```
// run the clock at 4x speed.
clock.speedFactor = 4
```

## Differences from `THREE.Clock()`

- The clock is initialized in stopped state.
- Uses getters. So it's `clock.elapsedTime` rather than `threeClock.getElapsedTime()`
!

CSS 

              
                body {
  background: #111;
  color: #fff;
  font-family: sans-serif;
  font-size: 1.25rem;
  line-height: 1.4;
}

h1 { color: deepskyblue; }
h2, h3 { color: mediumseagreen; }

pre {
  background: #000;
  padding: 1rem;
  color: #cfc;
  border-radius: .25rem;
}
!

JS 

              
                class SpeedClock {

  constructor() {
    this._startTime = NaN;
    this._totalElapsed = 0;
    this._running = false;
    this._speedFactor = 1;
  }

  /**
   * start the stopwatch
   * @returns {SpeedClock} instance
   */
  start(speedFactor) {
    if (this._running) {
      this.stop();
    }
    if (typeof speedFactor !== "undefined") {
      this._speedFactor = speedFactor;  
    }
    this._startTime = performance.now();
    this._running = true;
    return this;
  }

  /**
   * stop the stopwatch
   * @returns instance
   */
  stop() {
    if (this._running && !Number.isNaN(this._startTime)) {
      this._running = false;
      this._totalElapsed += (performance.now() - this._startTime) * this._speedFactor * 1e-3;
    }
    return this;
  }

  /**
   * reset the stopwatch
   * @returns instance
   */
  reset() {
    this._totalElapsed = 0;
    this._startTime = this._running ? performance.now() : NaN;
    return this;
  }

  /**
   * get run status
   * @returns {boolean} true if running
   */
  get running() {
    return this._running;
  }

  /**
   * get elapsed time
   * @returns {number} elapsed time
   */
  get elapsedTime() {
    return this._running
      ? this._totalElapsed + (performance.now() - this._startTime) * this._speedFactor * 1e-3
      : this._totalElapsed;
  }
  
  /**
   * get speed factor
   * @returns {number} speed factor
   */
  get speedFactor() {
    return this._speedFactor;
  }
  
  /**
   * set speed factor
   */
  set speedFactor(value) {
    this.stop().start(value);
  }
}
!
999px

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