BOLL (Bollinger Bands)

Bollinger Bands indicator.

Usage

const data = await sdk.getKlineWithIndicators('sz000858', {
  indicators: { boll: true }
});

data.forEach(k => {
  console.log(`Upper: ${k.boll?.upper}, Mid: ${k.boll?.mid}, Lower: ${k.boll?.lower}`);
});

Manual Calculation

import { calcBOLL } from 'stock-sdk';

const closes = [/* close prices */];
const result = calcBOLL(closes, 20, 2);

// result.upper - Upper band
// result.mid   - Middle band (MA)
// result.lower - Lower band

Parameters

Parameter	Default	Description
period	20	MA period
multiplier	2	Standard deviation multiplier

Formula

$$Middle = SMA_{20}$$ $$Upper = Middle + 2 \times \sigma$$ $$Lower = Middle - 2 \times \sigma$$

Where $\sigma$ is the standard deviation.