stock-indicator/src/idicators/dma.ts

Stock Indicator Library

import {
  funMA,
  funRound,
  TMixed,
  checkArrayOfNumbers,
  checkNumber,
} from "../common";

/**
 * DMA - Different of Moving Average
 * @param {number} CLOSE - closing prices of the stock
 * @param {number} N1 - number of periods for the first moving average, must be greater than 1 and less than or equal to the length of the CLOSE array,default is 10
 * @param {number} N2  - number of periods for the second moving average, must be greater than N1 and less than or equal to the length of the CLOSE array,default is 50
 * @param {number} M - number of periods for the moving average of the DIF, must be greater than 1 and less than or equal to the length of the DIF array,default is 10
 * @returns {{DIF: TMixed[], DIFMA: TMixed[]}} - DIF and DIFMA arrays, DIFMA is the moving average of the DIF array
 */
export function DMA(
  CLOSE: number[],
  N1: number = 10,
  N2: number = 50,
  M: number = 10
): { DIF: TMixed[]; DIFMA: TMixed[] } {
  // - check input data
  checkArrayOfNumbers(CLOSE, "CLOSE");
  checkNumber(N1, 2, CLOSE, "N1", "CLOSE");
  checkNumber(N1, N1, CLOSE, "N2", "CLOSE");
  checkNumber(M, 2, N2, "M", "N2");

  const maN1 = funMA(CLOSE, N1);
  const maN2 = funMA(CLOSE, N2);
  const DIF = maN1.map((item, index) =>
    item !== null && maN2[index] !== null
      ? funRound(item - maN2[index], 3)
      : null
  );
  const DIFMA = funMA(DIF, M).map((item) => funRound(item, 3));
  return { DIF, DIFMA };
}