getNumberSIPrefix.js

getNumberSIPrefix.js

export function getNumberSIPrefix(x, options = {}) {
  const FLOAT_POINT = options.floatLength || 1;
  const METIRC_GAP = options.metircGap || 1;
  const UNITS_STRING = [
    'million',
    'billion',
    'trillion',
    'quadrillion',
    'quintillion',
    'sextillion',
    'septillion',
    'octillion',
    'nonillion',
    'decillion',
    'undecillion',
    'duodecillion',
    'tredecillion',
    'quattuordecillion',
    'quindecillion',
    'sexdecillion',
    'septendecillion',
    'octodecillion',
    'novemdecillion',
    'vigintillion',
  ];
  const originNumberString = x.toLocaleString().replace(/(\,)/gi, '');
  const originNumberStringLength = originNumberString.length - 1;

  const unitIndex = originNumberStringLength / 3;
  // 10^0, 10^3 은 생략 (UNIT_STRING.length -2)
  const unit = UNITS_STRING[Math.floor(unitIndex) - 2 - METIRC_GAP];

  // units 의 규칙인 10^3n 승에 대해 남은 자릿수를 알게 하려 함
  // 딱 맞아 떨어지게 되면 자리수가 0개 가는건 오류이므로 +1 처리
  const substrLength = (originNumberStringLength % 3) + 1 + 3 * METIRC_GAP;

  const decimal = originNumberString.substr(0, unit && substrLength);
  const float = originNumberString.substr(substrLength, FLOAT_POINT);

  const combined = +`${decimal}.${float}`;

  return `${parseFloat(combined).toLocaleString()} ${unit || ''}`;
}