debian-mirror-gitlab/core-js/modules/es.number.to-fixed.js
2019-09-25 13:30:05 +05:30

126 lines
3.3 KiB
JavaScript

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