highcharts/js/indicators/ema.src.js

JavaScript charting framework

/**
 * @license  Highcharts JS v6.2.0 (2018-10-17)
 *
 * Indicator series type for Highstock
 *
 * (c) 2010-2017 Sebastian Bochan
 *
 * License: www.highcharts.com/license
 */
'use strict';
(function (factory) {
	if (typeof module === 'object' && module.exports) {
		module.exports = factory;
	} else if (typeof define === 'function' && define.amd) {
		define(function () {
			return factory;
		});
	} else {
		factory(Highcharts);
	}
}(function (Highcharts) {
	(function (H) {

		var isArray = H.isArray,
		    seriesType = H.seriesType;

		// Utils:
		function accumulateAverage(points, xVal, yVal, i, index) {
		    var xValue = xVal[i],
		        yValue = index < 0 ? yVal[i] : yVal[i][index];

		    points.push([xValue, yValue]);
		}

		function populateAverage(
		    points,
		    xVal,
		    yVal,
		    i,
		    EMApercent,
		    calEMA,
		    index,
		    SMA
		) {
		    var x = xVal[i - 1],
		        yValue = index < 0 ? yVal[i - 1] : yVal[i - 1][index],
		        y;

		    y = calEMA === undefined ?
		        SMA :
		        ((yValue * EMApercent) + (calEMA * (1 - EMApercent)));

		    return [x, y];
		}
		/**
		 * The EMA series type.
		 *
		 * @constructor seriesTypes.ema
		 * @augments seriesTypes.sma
		 */
		seriesType('ema', 'sma',
		    /**
		     * Exponential moving average indicator (EMA). This series requires the
		     * `linkedTo` option to be set.
		     *
		     * @extends plotOptions.sma
		     * @product highstock
		     * @sample {highstock} stock/indicators/ema
		     *                        Exponential moving average indicator
		     * @since 6.0.0
		     * @optionparent plotOptions.ema
		     */
		    {
		        params: {
		            index: 0,
		            period: 14
		        }
		    }, {
		        getValues: function (series, params) {
		            var period = params.period,
		                xVal = series.xData,
		                yVal = series.yData,
		                yValLen = yVal ? yVal.length : 0,
		                EMApercent = (2 / (period + 1)),
		                range = 0,
		                sum = 0,
		                EMA = [],
		                xData = [],
		                yData = [],
		                index = -1,
		                points = [],
		                SMA = 0,
		                calEMA,
		                EMAPoint,
		                i;

		            // Check period, if bigger than points length, skip
		            if (xVal.length < period) {
		                return false;
		            }

		            // Switch index for OHLC / Candlestick / Arearange
		            if (isArray(yVal[0])) {
		                index = params.index ? params.index : 0;
		            }

		            // Accumulate first N-points
		            while (range < period) {
		                accumulateAverage(points, xVal, yVal, range, index);
		                sum += index < 0 ? yVal[range] : yVal[range][index];
		                range++;
		            }

		            // first point
		            SMA = sum / period;

		            // Calculate value one-by-one for each period in visible data
		            for (i = range; i < yValLen; i++) {
		                EMAPoint = populateAverage(
		                    points,
		                    xVal,
		                    yVal,
		                    i,
		                    EMApercent,
		                    calEMA,
		                    index,
		                    SMA
		                );
		                EMA.push(EMAPoint);
		                xData.push(EMAPoint[0]);
		                yData.push(EMAPoint[1]);
		                calEMA = EMAPoint[1];

		                accumulateAverage(points, xVal, yVal, i, index);
		            }

		            EMAPoint = populateAverage(
		                points,
		                xVal,
		                yVal,
		                i,
		                EMApercent,
		                calEMA,
		                index
		            );
		            EMA.push(EMAPoint);
		            xData.push(EMAPoint[0]);
		            yData.push(EMAPoint[1]);

		            return {
		                values: EMA,
		                xData: xData,
		                yData: yData
		            };
		        }
		    });

		/**
		 * A `EMA` series. If the [type](#series.ema.type) option is not
		 * specified, it is inherited from [chart.type](#chart.type).
		 *
		 * @type {Object}
		 * @since 6.0.0
		 * @extends series,plotOptions.ema
		 * @excluding data,dataParser,dataURL
		 * @product highstock
		 * @apioption series.ema
		 */

		/**
		 * @type {Array<Object|Array>}
		 * @since 6.0.0
		 * @extends series.sma.data
		 * @product highstock
		 * @apioption series.ema.data
		 */

	}(Highcharts));
	return (function () {


	}());
}));