function roundToInt(value, mode) { let tmp = Math.floor(Math.abs(value) + 0.5) if ( (mode === 'PHP_ROUND_HALF_DOWN' && value === tmp - 0.5) || (mode === 'PHP_ROUND_HALF_EVEN' && value === 0.5 + 2 * Math.floor(tmp / 2)) || (mode === 'PHP_ROUND_HALF_ODD' && value === 0.5 + 2 * Math.floor(tmp / 2) - 1) ) { tmp -= 1 } return value < 0 ? -tmp : tmp } module.exports = function round(value, precision = 0, mode = 'PHP_ROUND_HALF_UP') { // discuss at: https://locutus.io/php/round/ // original by: Philip Peterson // revised by: Onno Marsman (https://twitter.com/onnomarsman) // revised by: T.Wild // revised by: Rafał Kukawski (https://blog.kukawski.pl) // input by: Greenseed // input by: meo // input by: William // input by: Josep Sanz (https://www.ws3.es/) // bugfixed by: Brett Zamir (https://brett-zamir.me) // revised by: Rafał Kukawski // example 1: round(1241757, -3) // returns 1: 1242000 // example 2: round(3.6) // returns 2: 4 // example 3: round(2.835, 2) // returns 3: 2.84 // example 4: round(1.1749999999999, 2) // returns 4: 1.17 // example 5: round(58551.799999999996, 2) // returns 5: 58551.8 // example 6: round(4096.485, 2) // returns 6: 4096.49 const floatCast = require('../_helpers/_php_cast_float') const intCast = require('../_helpers/_php_cast_int') let p // the code is heavily based on the native PHP implementation // https://github.com/php/php-src/blob/PHP-7.4/ext/standard/math.c#L355 value = floatCast(value) precision = intCast(precision) p = Math.pow(10, precision) if (isNaN(value) || !isFinite(value)) { return value } // if value already integer and positive precision // then nothing to do, return early if (Math.trunc(value) === value && precision >= 0) { return value } // PHP does a pre-rounding before rounding to desired precision // https://wiki.php.net/rfc/rounding#pre-rounding_to_the_value_s_precision_if_possible const preRoundPrecision = 14 - Math.floor(Math.log10(Math.abs(value))) if (preRoundPrecision > precision && preRoundPrecision - 15 < precision) { value = roundToInt(value * Math.pow(10, preRoundPrecision), mode) value /= Math.pow(10, Math.abs(precision - preRoundPrecision)) } else { value *= p } value = roundToInt(value, mode) return value / p }