UNPKG

luhn-generator

Version:

A generator of numbers that passes the validation of Luhn algorithm or Luhn formula, also known as the 'modulus 10' or 'mod 10' algorithm

115 lines (112 loc) 2.77 kB
'use strict'; var $export = require('./_export'); var toInteger = require('./_to-integer'); var aNumberValue = require('./_a-number-value'); var repeat = require('./_string-repeat'); var $toFixed = 1.0.toFixed; var floor = Math.floor; var data = [0, 0, 0, 0, 0, 0]; var ERROR = 'Number.toFixed: incorrect invocation!'; var ZERO = '0'; var multiply = function (n, c) { var i = -1; var c2 = c; while (++i < 6) { c2 += n * data[i]; data[i] = c2 % 1e7; c2 = floor(c2 / 1e7); } }; var divide = function (n) { var i = 6; var c = 0; while (--i >= 0) { c += data[i]; data[i] = floor(c / n); c = (c % n) * 1e7; } }; var numToString = function () { var i = 6; var s = ''; while (--i >= 0) { if (s !== '' || i === 0 || data[i] !== 0) { var t = String(data[i]); s = s === '' ? t : s + repeat.call(ZERO, 7 - t.length) + t; } } return s; }; var pow = function (x, n, acc) { return n === 0 ? acc : n % 2 === 1 ? pow(x, n - 1, acc * x) : pow(x * x, n / 2, acc); }; var log = function (x) { var n = 0; var x2 = x; while (x2 >= 4096) { n += 12; x2 /= 4096; } while (x2 >= 2) { n += 1; x2 /= 2; } return n; }; $export($export.P + $export.F * (!!$toFixed && ( 0.00008.toFixed(3) !== '0.000' || 0.9.toFixed(0) !== '1' || 1.255.toFixed(2) !== '1.25' || 1000000000000000128.0.toFixed(0) !== '1000000000000000128' ) || !require('./_fails')(function () { // V8 ~ Android 4.3- $toFixed.call({}); })), 'Number', { toFixed: function toFixed(fractionDigits) { var x = aNumberValue(this, ERROR); var f = toInteger(fractionDigits); var s = ''; var m = ZERO; var e, z, j, k; if (f < 0 || f > 20) throw RangeError(ERROR); // eslint-disable-next-line no-self-compare if (x != x) return 'NaN'; if (x <= -1e21 || x >= 1e21) return String(x); if (x < 0) { s = '-'; x = -x; } if (x > 1e-21) { e = log(x * pow(2, 69, 1)) - 69; z = e < 0 ? x * pow(2, -e, 1) : x / pow(2, e, 1); z *= 0x10000000000000; e = 52 - e; if (e > 0) { multiply(0, z); j = f; while (j >= 7) { multiply(1e7, 0); j -= 7; } multiply(pow(10, j, 1), 0); j = e - 1; while (j >= 23) { divide(1 << 23); j -= 23; } divide(1 << j); multiply(1, 1); divide(2); m = numToString(); } else { multiply(0, z); multiply(1 << -e, 0); m = numToString() + repeat.call(ZERO, f); } } if (f > 0) { k = m.length; m = s + (k <= f ? '0.' + repeat.call(ZERO, f - k) + m : m.slice(0, k - f) + '.' + m.slice(k - f)); } else { m = s + m; } return m; } });