highcharts
Version:
JavaScript charting framework
138 lines (137 loc) • 3.87 kB
JavaScript
/* *
*
* License: www.highcharts.com/license
*
* !!!!!!! SOURCE GETS TRANSPILED BY TYPESCRIPT. EDIT TS FILE ONLY. !!!!!!!
*
* */
;
import SeriesRegistry from '../../../Core/Series/SeriesRegistry.js';
const { sma: SMAIndicator } = SeriesRegistry.seriesTypes;
import U from '../../../Core/Utilities.js';
const { correctFloat, isArray, merge } = U;
/* *
*
* Class
*
* */
/**
* The EMA series type.
*
* @private
* @class
* @name Highcharts.seriesTypes.ema
*
* @augments Highcharts.Series
*/
class EMAIndicator extends SMAIndicator {
/* *
*
* Functions
*
* */
accumulatePeriodPoints(period, index, yVal) {
let sum = 0, i = 0, y = 0;
while (i < period) {
y = index < 0 ? yVal[i] : yVal[i][index];
sum = sum + y;
i++;
}
return sum;
}
calculateEma(xVal, yVal, i, EMApercent, calEMA, index, SMA) {
const x = xVal[i - 1], yValue = index < 0 ?
yVal[i - 1] :
yVal[i - 1][index], y = typeof calEMA === 'undefined' ?
SMA : correctFloat((yValue * EMApercent) +
(calEMA * (1 - EMApercent)));
return [x, y];
}
getValues(series, params) {
const period = params.period, xVal = series.xData, yVal = series.yData, yValLen = yVal ? yVal.length : 0, EMApercent = 2 / (period + 1), EMA = [], xData = [], yData = [];
let calEMA, EMAPoint, i, index = -1, sum = 0, SMA = 0;
// Check period, if bigger than points length, skip
if (yValLen < period) {
return;
}
// Switch index for OHLC / Candlestick / Arearange
if (isArray(yVal[0])) {
index = params.index ? params.index : 0;
}
// Accumulate first N-points
sum = this.accumulatePeriodPoints(period, index, yVal);
// First point
SMA = sum / period;
// Calculate value one-by-one for each period in visible data
for (i = period; i < yValLen + 1; i++) {
EMAPoint = this.calculateEma(xVal, yVal, i, EMApercent, calEMA, index, SMA);
EMA.push(EMAPoint);
xData.push(EMAPoint[0]);
yData.push(EMAPoint[1]);
calEMA = EMAPoint[1];
}
return {
values: EMA,
xData: xData,
yData: yData
};
}
}
/* *
*
* Static Properties
*
* */
/**
* Exponential moving average indicator (EMA). This series requires the
* `linkedTo` option to be set.
*
* @sample stock/indicators/ema
* Exponential moving average indicator
*
* @extends plotOptions.sma
* @since 6.0.0
* @product highstock
* @requires stock/indicators/indicators
* @optionparent plotOptions.ema
*/
EMAIndicator.defaultOptions = merge(SMAIndicator.defaultOptions, {
params: {
/**
* The point index which indicator calculations will base. For
* example using OHLC data, index=2 means the indicator will be
* calculated using Low values.
*
* By default index value used to be set to 0. Since
* Highcharts Stock 7 by default index is set to 3
* which means that the ema indicator will be
* calculated using Close values.
*/
index: 3,
period: 9 // @merge 14 in v6.2
}
});
SeriesRegistry.registerSeriesType('ema', EMAIndicator);
/* *
*
* Default Export
*
* */
export default EMAIndicator;
/* *
*
* API Options
*
* */
/**
* A `EMA` series. If the [type](#series.ema.type) option is not
* specified, it is inherited from [chart.type](#chart.type).
*
* @extends series,plotOptions.ema
* @since 6.0.0
* @product highstock
* @excluding dataParser, dataURL
* @requires stock/indicators/indicators
* @apioption series.ema
*/
''; // Adds doclet above to the transpiled file