126 lines
3.3 KiB
JavaScript
126 lines
3.3 KiB
JavaScript
'use strict';
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var $ = require('../internals/export');
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var toInteger = require('../internals/to-integer');
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var thisNumberValue = require('../internals/this-number-value');
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var repeat = require('../internals/string-repeat');
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var fails = require('../internals/fails');
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var nativeToFixed = 1.0.toFixed;
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var floor = Math.floor;
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var pow = function (x, n, acc) {
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return n === 0 ? acc : n % 2 === 1 ? pow(x, n - 1, acc * x) : pow(x * x, n / 2, acc);
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};
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var log = function (x) {
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var n = 0;
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var x2 = x;
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while (x2 >= 4096) {
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n += 12;
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x2 /= 4096;
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}
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while (x2 >= 2) {
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n += 1;
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x2 /= 2;
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} return n;
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};
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var FORCED = nativeToFixed && (
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0.00008.toFixed(3) !== '0.000' ||
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0.9.toFixed(0) !== '1' ||
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1.255.toFixed(2) !== '1.25' ||
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1000000000000000128.0.toFixed(0) !== '1000000000000000128'
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) || !fails(function () {
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// V8 ~ Android 4.3-
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nativeToFixed.call({});
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});
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// `Number.prototype.toFixed` method
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// https://tc39.github.io/ecma262/#sec-number.prototype.tofixed
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$({ target: 'Number', proto: true, forced: FORCED }, {
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// eslint-disable-next-line max-statements
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toFixed: function toFixed(fractionDigits) {
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var number = thisNumberValue(this);
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var fractDigits = toInteger(fractionDigits);
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var data = [0, 0, 0, 0, 0, 0];
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var sign = '';
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var result = '0';
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var e, z, j, k;
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var multiply = function (n, c) {
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var index = -1;
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var c2 = c;
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while (++index < 6) {
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c2 += n * data[index];
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data[index] = c2 % 1e7;
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c2 = floor(c2 / 1e7);
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}
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};
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var divide = function (n) {
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var index = 6;
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var c = 0;
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while (--index >= 0) {
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c += data[index];
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data[index] = floor(c / n);
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c = (c % n) * 1e7;
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}
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};
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var dataToString = function () {
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var index = 6;
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var s = '';
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while (--index >= 0) {
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if (s !== '' || index === 0 || data[index] !== 0) {
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var t = String(data[index]);
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s = s === '' ? t : s + repeat.call('0', 7 - t.length) + t;
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}
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} return s;
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};
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if (fractDigits < 0 || fractDigits > 20) throw RangeError('Incorrect fraction digits');
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// eslint-disable-next-line no-self-compare
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if (number != number) return 'NaN';
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if (number <= -1e21 || number >= 1e21) return String(number);
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if (number < 0) {
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sign = '-';
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number = -number;
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}
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if (number > 1e-21) {
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e = log(number * pow(2, 69, 1)) - 69;
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z = e < 0 ? number * pow(2, -e, 1) : number / pow(2, e, 1);
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z *= 0x10000000000000;
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e = 52 - e;
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if (e > 0) {
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multiply(0, z);
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j = fractDigits;
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while (j >= 7) {
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multiply(1e7, 0);
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j -= 7;
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}
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multiply(pow(10, j, 1), 0);
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j = e - 1;
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while (j >= 23) {
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divide(1 << 23);
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j -= 23;
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}
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divide(1 << j);
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multiply(1, 1);
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divide(2);
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result = dataToString();
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} else {
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multiply(0, z);
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multiply(1 << -e, 0);
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result = dataToString() + repeat.call('0', fractDigits);
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}
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}
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if (fractDigits > 0) {
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k = result.length;
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result = sign + (k <= fractDigits
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? '0.' + repeat.call('0', fractDigits - k) + result
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: result.slice(0, k - fractDigits) + '.' + result.slice(k - fractDigits));
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} else {
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result = sign + result;
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} return result;
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}
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});
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