bennycode · bennycode · Dec 27, 2021 · Dec 27, 2021
diff --git a/src/BBW/BollingerBandsWidth.test.ts b/src/BBW/BollingerBandsWidth.test.ts
@@ -3,7 +3,7 @@ import {BollingerBandsWidth, FasterBollingerBandsWidth} from './BollingerBandsWi
 
 describe('BollingerBandsWidth', () => {
   describe('getResult', () => {
-    it('calculates the Bollinger Bands Width', () => {
+    it('calculates the Bollinger Bands Width (BBW)', () => {
       // eBay Inc. (EBAY) daily stock prices in USD on NASDAQ with CBOE BZX exchange
       const candles = [
         {open: 72.06, high: 72.07, low: 68.08, close: 68.21}, // 2021/07/30

diff --git a/src/STOCH/StochasticOscillator.test.ts b/src/STOCH/StochasticOscillator.test.ts
@@ -1,96 +1,107 @@
-import {StochasticOscillator} from './StochasticOscillator';
+import {FasterStochasticOscillator, StochasticOscillator} from './StochasticOscillator';
 import {NotEnoughDataError} from '../error';
 
 describe('StochasticOscillator', () => {
   describe('update', () => {
-    it('is stable when the amount of inputs is bigger than the required interval', () => {
+    it('calculates the StochasticOscillator', () => {
       // Test data verified with:
-      // https://runkit.com/anandaravindan/stochastic
-      const highs = [
-        127.009, 127.616, 126.591, 127.347, 128.173, 128.432, 127.367, 126.422, 126.9, 126.85, 125.646, 125.716,
-        127.158, 127.715, 127.686, 128.223, 128.273, 128.093, 128.273, 127.735, 128.77, 129.287, 130.063, 129.118,
-        129.287, 128.472, 128.093, 128.651, 129.138, 128.641,
-      ];
-      const lows = [
-        125.357, 126.163, 124.93, 126.094, 126.82, 126.482, 126.034, 124.83, 126.392, 125.716, 124.562, 124.572,
-        125.069, 126.86, 126.631, 126.8, 126.711, 126.8, 126.134, 125.925, 126.989, 127.815, 128.472, 128.064, 127.606,
-        127.596, 126.999, 126.9, 127.487, 127.397,
-      ];
-      const closes = [
-        125.357, 126.163, 124.93, 126.094, 126.82, 126.482, 126.034, 124.83, 126.392, 125.716, 124.562, 124.572,
-        125.069, 127.288, 127.178, 128.014, 127.109, 127.725, 127.059, 127.327, 128.71, 127.875, 128.581, 128.601,
-        127.934, 128.113, 127.596, 127.596, 128.69, 128.273,
+      // https://tulipindicators.org/stoch
+      const candles = [
+        {high: 82.15, low: 81.29, close: 81.59},
+        {high: 81.89, low: 80.64, close: 81.06},
+        {high: 83.03, low: 81.31, close: 82.87},
+        {high: 83.3, low: 82.65, close: 83.0},
+        {high: 83.85, low: 83.07, close: 83.61},
+        {high: 83.9, low: 83.11, close: 83.15},
+        {high: 83.33, low: 82.49, close: 82.84},
+        {high: 84.3, low: 82.3, close: 83.99},
+        {high: 84.84, low: 84.15, close: 84.55},
+        {high: 85.0, low: 84.11, close: 84.36},
+        {high: 85.9, low: 84.03, close: 85.53},
+        {high: 86.58, low: 85.39, close: 86.54},
+        {high: 86.98, low: 85.76, close: 86.89},
+        {high: 88.0, low: 87.17, close: 87.77},
+        {high: 87.87, low: 87.01, close: 87.29},
       ];
 
-      const expectations = [
-        {d: '75.75', k: '89.20'},
-        {d: '74.20', k: '65.81'},
-        {d: '78.91', k: '81.73'},
-        {d: '70.69', k: '64.52'},
-        {d: '73.59', k: '74.51'},
-        {d: '79.20', k: '98.57'},
-        {d: '81.07', k: '70.12'},
-        {d: '80.58', k: '73.06'},
-        {d: '72.20', k: '73.42'},
-        {d: '69.24', k: '61.23'},
-        {d: '65.20', k: '60.95'},
-        {d: '54.19', k: '40.38'},
-        {d: '47.24', k: '40.38'},
-        {d: '49.19', k: '66.82'},
-        {d: '54.65', k: '56.74'},
-      ];
+      const stochKs = ['77.39', '83.13', '84.87', '88.36', '95.25', '96.74', '91.09'];
+
+      const stochDs = ['75.70', '78.01', '81.79', '85.45', '89.49', '93.45', '94.36'];
+
+      const stoch = new StochasticOscillator(5, 3, 3);
+      const fasterStoch = new FasterStochasticOscillator(5, 3, 3);
 
-      const stoch = new StochasticOscillator(14, 3);
-
-      for (let i = 0; i < highs.length; i++) {
-        stoch.update({
-          close: closes[i],
-          high: highs[i],
-          low: lows[i],
-        });
-        if (stoch.isStable) {
-          const {k, d} = stoch.getResult();
-          const expected = expectations.shift()!;
-          expect(k.toFixed(2)).toBe(expected.k);
-          expect(d.toFixed(2)).toBe(expected.d);
+      for (const candle of candles) {
+        const stochResult = stoch.update(candle);
+        const fasterStochResult = fasterStoch.update(candle);
+        if (fasterStoch.isStable && fasterStochResult && stoch.isStable && stochResult) {
+          const stochD = stochDs.shift()!;
+          const stochK = stochKs.shift()!;
+
+          expect(stochResult.stochD.toFixed(2)).toEqual(stochD);
+          expect(fasterStochResult.stochD.toFixed(2)).toEqual(stochD);
+
+          expect(stochResult.stochD.toFixed(2)).toEqual(stochD);
+          expect(fasterStochResult.stochK.toFixed(2)).toEqual(stochK);
         }
       }
 
-      const {k, d} = stoch.getResult();
-      expect(k.toFixed(2)).toBe('56.74');
-      expect(d.toFixed(2)).toBe('54.65');
+      expect(stoch.isStable).toBeTrue();
+      expect(fasterStoch.isStable).toBeTrue();
+
+      expect(stoch.getResult().stochK.toFixed(2)).toBe('91.09');
+      expect(fasterStoch.getResult().stochK.toFixed(2)).toBe('91.09');
     });
   });
 
   describe('getResult', () => {
     it('throws an error when there is not enough input data', () => {
-      const stoch = new StochasticOscillator(5, 3);
+      const stoch = new StochasticOscillator(5, 3, 3);
+
+      stoch.update({close: 1, high: 1, low: 1});
+      stoch.update({close: 1, high: 2, low: 1});
+      stoch.update({close: 1, high: 3, low: 1});
+      stoch.update({close: 1, high: 4, low: 1});
+      stoch.update({close: 1, high: 5, low: 1}); // Emits 1st of 3 required values for %d period
+      stoch.update({close: 1, high: 6, low: 1}); // Emits 2nd of 3 required values for %d period
 
       try {
-        stoch.update({close: 1, high: 1, low: 1});
-        stoch.update({close: 1, high: 2, low: 1});
-        stoch.update({close: 1, high: 3, low: 1});
-        stoch.update({close: 1, high: 4, low: 1});
-        stoch.update({close: 1, high: 5, low: 1}); // Emits 1st of 3 required values for %d period
-        stoch.update({close: 1, high: 6, low: 1}); // Emits 2nd of 3 required values for %d period
         stoch.getResult();
         fail('Expected error');
       } catch (error) {
         expect(error).toBeInstanceOf(NotEnoughDataError);
       }
+
+      const fasterStoch = new FasterStochasticOscillator(5, 3, 3);
+
+      try {
+        fasterStoch.getResult();
+        fail('Expected error');
+      } catch (error) {
+        expect(error).toBeInstanceOf(NotEnoughDataError);
+      }
     });
 
     it('prevents division by zero errors when highest high and lowest low have the same value', () => {
-      const stoch = new StochasticOscillator(5, 3);
+      const stoch = new StochasticOscillator(5, 3, 3);
+      stoch.update({close: 100, high: 100, low: 100});
+      stoch.update({close: 100, high: 100, low: 100});
       stoch.update({close: 100, high: 100, low: 100});
       stoch.update({close: 100, high: 100, low: 100});
       stoch.update({close: 100, high: 100, low: 100});
       stoch.update({close: 100, high: 100, low: 100});
       stoch.update({close: 100, high: 100, low: 100});
       stoch.update({close: 100, high: 100, low: 100});
       const result = stoch.update({close: 100, high: 100, low: 100})!;
-      expect(result.k.toFixed(2)).toBe('0.00');
-      expect(result.d.toFixed(2)).toBe('0.00');
+      expect(result.stochK.toFixed(2)).toBe('0.00');
+      expect(result.stochD.toFixed(2)).toBe('0.00');
+
+      const fasterStoch = new FasterStochasticOscillator(1, 2, 2);
+      fasterStoch.update({close: 100, high: 100, low: 100});
+      fasterStoch.update({close: 100, high: 100, low: 100});
+      const {stochK, stochD} = fasterStoch.getResult();
+      expect(stochK.toFixed(2)).toBe('0.00');
+      expect(stochD.toFixed(2)).toBe('0.00');
     });
   });
 });
diff --git a/src/STOCH/StochasticOscillator.ts b/src/STOCH/StochasticOscillator.ts
@@ -1,16 +1,23 @@
 import {Indicator} from '../Indicator';
 import Big from 'big.js';
-import {SMA} from '../SMA/SMA';
-import {MovingAverageTypes} from '../MA/MovingAverageTypes';
-import {MovingAverage} from '../MA/MovingAverage';
+import {FasterSMA, SMA} from '../SMA/SMA';
 import {getMaximum} from '../util/getMaximum';
 import {getMinimum} from '../util/getMinimum';
 import {NotEnoughDataError} from '../error';
-import {HighLowClose} from '../util';
+import {HighLowClose, HighLowCloseNumber} from '../util';
 
 export interface StochasticResult {
-  d: Big;
-  k: Big;
+  /** Slow stochastic indicator (%D) */
+  stochD: Big;
+  /** Fast stochastic indicator (%K) */
+  stochK: Big;
+}
+
+export interface FasterStochasticResult {
+  /** Slow stochastic indicator (%D) */
+  stochD: number;
+  /** Fast stochastic indicator (%K) */
+  stochK: number;
 }
 
 /**
@@ -19,32 +26,34 @@ export interface StochasticResult {
  *
  * The Stochastic Oscillator was developed by George Lane and is range-bound between 0 and 100. The Stochastic
  * Oscillator attempts to predict price turning points. A value of 80 indicates that the asset is on the verge of being
- * overbought. By default a Simple Moving Average (SMA) is used. When the momentum starts to slow down, the Stochastic
+ * overbought. By default, a Simple Moving Average (SMA) is used. When the momentum starts to slow down, the Stochastic
  * Oscillator values start to turn down. In the case of an uptrend, prices tend to make higher highs, and the
  * settlement price usually tends to be in the upper end of that time period's trading range.
  *
- * The %k values represent the relation between current close to the period's price range (high/low). It is sometimes
- * referred as the "fast" stochastic period (fastk). The %d values represent a Moving Average of the %k values. It
- * is sometimes referred as the "slow" period.
+ * The stochastic k (%k) values represent the relation between current close to the period's price range (high/low). It
+ * is sometimes referred as the "fast" stochastic period (fastk). The stochastic d (%d) values represent a Moving
+ * Average of the %k values. It is sometimes referred as the "slow" period.
  *
  * @see https://en.wikipedia.org/wiki/Stochastic_oscillator
  * @see https://www.investopedia.com/terms/s/stochasticoscillator.asp
  */
 export class StochasticOscillator implements Indicator<StochasticResult, HighLowClose> {
-  public readonly d: MovingAverage;
+  private readonly periodM: SMA;
+  private readonly periodP: SMA;
 
   private readonly candles: HighLowClose[] = [];
   private result?: StochasticResult;
 
   /**
    * Constructs a Stochastic Oscillator.
    *
-   * @param periodK Typical intervals for the %k period are 5, 9, or 14
-   * @param periodD The standard interval for the %d period is 3
-   * @param [Indicator] Moving average type to smooth values (%d period)
+   * @param n The %k period
+   * @param m The %k slowing period
+   * @param p The %d period
    */
-  constructor(public readonly periodK: number, public readonly periodD: number, Indicator: MovingAverageTypes = SMA) {
-    this.d = new Indicator(periodD);
+  constructor(public readonly n: number, public readonly m: number, public readonly p: number) {
+    this.periodM = new SMA(m);
+    this.periodP = new SMA(p);
   }
 
   getResult(): StochasticResult {
@@ -55,25 +64,26 @@ export class StochasticOscillator implements Indicator<StochasticResult, HighLow
     return this.result;
   }
 
-  update(candle: HighLowClose): StochasticResult | void {
+  update(candle: HighLowClose): void | StochasticResult {
     this.candles.push(candle);
 
-    if (this.candles.length > this.periodK) {
+    if (this.candles.length > this.n) {
       this.candles.shift();
     }
 
-    if (this.candles.length === this.periodK) {
+    if (this.candles.length === this.n) {
       const highest = getMaximum(this.candles.map(candle => candle.high));
       const lowest = getMinimum(this.candles.map(candle => candle.low));
       const divisor = new Big(highest).minus(lowest);
       let fastK = new Big(100).mul(new Big(candle.close).minus(lowest));
       // Prevent division by zero
       fastK = fastK.div(divisor.eq(0) ? 1 : divisor);
-      const dResult = this.d.update(fastK);
-      if (dResult) {
+      const stochK = this.periodM.update(fastK); // (stoch_k, %k)
+      const stochD = stochK && this.periodP.update(stochK); // (stoch_d, %d)
+      if (stochK && stochD) {
         return (this.result = {
-          d: dResult,
-          k: fastK,
+          stochD,
+          stochK,
         });
       }
     }
@@ -83,3 +93,57 @@ export class StochasticOscillator implements Indicator<StochasticResult, HighLow
     return this.result !== undefined;
   }
 }
+
+export class FasterStochasticOscillator implements Indicator<FasterStochasticResult, HighLowCloseNumber> {
+  public readonly candles: HighLowCloseNumber[] = [];
+  private result: FasterStochasticResult | undefined;
+  private readonly periodM: FasterSMA;
+  private readonly periodP: FasterSMA;
+
+  /**
+   * @param n The %k period
+   * @param m The %k slowing period
+   * @param p The %d period
+   */
+  constructor(public n: number, public m: number, public p: number) {
+    this.periodM = new FasterSMA(m);
+    this.periodP = new FasterSMA(p);
+  }
+
+  getResult(): FasterStochasticResult {
+    if (this.result === undefined) {
+      throw new NotEnoughDataError();
+    }
+
+    return this.result;
+  }
+
+  get isStable(): boolean {
+    return this.result !== undefined;
+  }
+
+  update(candle: HighLowCloseNumber): void | FasterStochasticResult {
+    this.candles.push(candle);
+
+    if (this.candles.length > this.n) {
+      this.candles.shift();
+    }
+
+    if (this.candles.length === this.n) {
+      const highest = Math.max(...this.candles.map(candle => candle.high));
+      const lowest = Math.min(...this.candles.map(candle => candle.low));
+      const divisor = highest - lowest;
+      let fastK = (candle.close - lowest) * 100;
+      // Prevent division by zero
+      fastK = fastK / (divisor === 0 ? 1 : divisor);
+      const stochK = this.periodM.update(fastK); // (stoch_k, %k)
+      const stochD = stochK && this.periodP.update(stochK); // (stoch_d, %d)
+      if (stochK !== undefined && stochD !== undefined) {
+        return (this.result = {
+          stochD,
+          stochK,
+        });
+      }
+    }
+  }
+}
diff --git a/src/start/startBenchmark.ts b/src/start/startBenchmark.ts
@@ -34,6 +34,7 @@ import {
   FasterROC,
   FasterRSI,
   FasterSMA,
+  FasterStochasticOscillator,
   FasterStochasticRSI,
   FasterTR,
   FasterWSMA,
@@ -49,6 +50,7 @@ import {
   ROC,
   RSI,
   SMA,
+  StochasticOscillator,
   StochasticRSI,
   TR,
   WSMA,
@@ -310,6 +312,18 @@ new Benchmark.Suite('Technical Indicators')
       fasterSMA.update(price);
     }
   })
+  .add('StochasticOscillator', () => {
+    const stoch = new StochasticOscillator(shortInterval, interval, interval);
+    for (const candle of candles) {
+      stoch.update(candle);
+    }
+  })
+  .add('FasterStochasticOscillator', () => {
+    const fasterStoch = new FasterStochasticOscillator(shortInterval, interval, interval);
+    for (const candle of highLowCloses) {
+      fasterStoch.update(candle);
+    }
+  })
   .add('StochasticRSI', () => {
     const stochRSI = new StochasticRSI(interval);
     for (const price of prices) {