trip.three/lib/util/decimalAdjust.js

Three.js addon for Trip

'use strict';

// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/round

/**
 * Decimal adjustment of a number.
 *
 * @param {Number}  value The number.
 * @param {Integer} exp   The exponent (the 10 logarithm of the adjustment base).
 * @returns {Number} The adjusted value.
 */

function decimalAdjust(value, exp) {
  // If the exp is undefined or zero...
  if (typeof exp === 'undefined' || +exp === 0) {
    return Math.round(value);
  }
  value = +value;
  exp = +exp;
  // If the value is not a number or the exp is not an integer...
  if (isNaN(value) || !(typeof exp === 'number' && exp % 1 === 0)) {
    return NaN;
  }
  // Shift
  value = value.toString().split('e');
  value = Math.round(+(value[0] + 'e' + (value[1] ? +value[1] - exp : -exp)));
  // Shift back
  value = value.toString().split('e');
  return +(value[0] + 'e' + (value[1] ? +value[1] + exp : exp));
}

module.exports = decimalAdjust;