@nickfaughey/format-si-prefix/dist/index.js

Format and unformat numbers with SI prefixes

'use strict';

Object.defineProperty(exports, '__esModule', {
  value: true
});

var _slicedToArray = (function () { function sliceIterator(arr, i) { var _arr = []; var _n = true; var _d = false; var _e = undefined; try { for (var _i = arr[Symbol.iterator](), _s; !(_n = (_s = _i.next()).done); _n = true) { _arr.push(_s.value); if (i && _arr.length === i) break; } } catch (err) { _d = true; _e = err; } finally { try { if (!_n && _i['return']) _i['return'](); } finally { if (_d) throw _e; } } return _arr; } return function (arr, i) { if (Array.isArray(arr)) { return arr; } else if (Symbol.iterator in Object(arr)) { return sliceIterator(arr, i); } else { throw new TypeError('Invalid attempt to destructure non-iterable instance'); } }; })();

exports.formatSI = formatSI;
exports.unformatSI = unformatSI;

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { 'default': obj }; }

var _parseunit = require('parseunit');

var _parseunit2 = _interopRequireDefault(_parseunit);

var PREFIXES = {
  '24': 'Y',
  '21': 'Z',
  '18': 'E',
  '15': 'P',
  '12': 'T',
  '9': 'G',
  '6': 'M',
  '3': 'k',
  '0': '',
  '-3': 'm',
  '-6': 'µ',
  '-9': 'n',
  '-12': 'p',
  '-15': 'f',
  '-18': 'a',
  '-21': 'z',
  '-24': 'y'
};

/**
 * 
 * @param {Number} num 
 * @param {Object} options 
 * @param {Boolean} options.space Determines whether a space will be inserted between the number and prefix. Default false.
 * @param {Boolean} options.sign Forces the + sign to be prepended to the output string if the number is positive. Default false.
 * @param {String} options.suffix Optionally adds a suffix to the output string for units.
 * @param {Number} options.places Number of decimal places to round to. Default 2.
 */

function formatSI(num) {
  var options = arguments.length <= 1 || arguments[1] === undefined ? {} : arguments[1];

  var str = '';
  var exponent = 0;

  if (num === 0) {
    str = '0';
  } else {
    var sig = Math.abs(num); // significand
    while (sig >= 1000 && exponent < 24) {
      sig /= 1000;
      exponent += 3;
    }
    while (sig < 1 && exponent > -24) {
      sig *= 1000;
      exponent -= 3;
    }

    var signPrefix = num < 0 ? '-' : '';
    if (sig > 1000) {
      // exponent == 24
      // significand can be arbitrarily long
      return signPrefix + sig.toFixed(0) + PREFIXES[exponent];
    }

    var places = options.hasOwnProperty('places') ? options.places : 2;
    str = signPrefix + sig.toFixed(places);
  }

  if (options.hasOwnProperty('space') && options.space) {
    str += ' ';
  }

  if (num !== 0) {
    str += PREFIXES[exponent];
  }

  if (options.hasOwnProperty('suffix')) {
    str += options.suffix;
  }

  if (options.hasOwnProperty('sign') && options.sign) {
    if (num >= 0) {
      str = '+' + str;
    }
  }

  return str;
}

var MULTIPLIERS = {
  Y: 1e24,
  Z: 1e21,
  E: 1e18,
  P: 1e15,
  T: 1e12,
  G: 1e9,
  M: 1e6,
  k: 1e3,
  '': 1,
  m: 1e-3,
  µ: 1e-6,
  u: 1e-6,
  n: 1e-9,
  p: 1e-12,
  f: 1e-15,
  a: 1e-18,
  z: 1e-21,
  y: 1e-24
};

function unformatSI(string) {
  if (string == null || string === '') {
    return NaN;
  }

  var _parseUnit = (0, _parseunit2['default'])(string);

  var _parseUnit2 = _slicedToArray(_parseUnit, 2);

  var val = _parseUnit2[0];
  var unit = _parseUnit2[1];

  var multiplier = MULTIPLIERS[unit];
  return val * multiplier;
}