locutus/golang/time/Truncate.js

Locutus other languages' standard libraries to JavaScript for fun and educational purposes

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.Truncate = Truncate;
const toTimeDate = (value) => {
    const date = value instanceof Date ? new Date(value.getTime()) : new Date(value);
    if (Number.isNaN(date.getTime())) {
        throw new TypeError('Truncate(): invalid date input');
    }
    return date;
};
function Truncate(value, unitMs) {
    //      discuss at: https://locutus.io/golang/time/Truncate
    // parity verified: Go 1.23
    //     original by: Kevin van Zonneveld (https://kvz.io)
    //          note 1: Truncates an instant to a lower multiple of `unitMs`.
    //       example 1: Truncate('2026-03-03T13:14:15.600Z', 1000).toISOString()
    //       returns 1: '2026-03-03T13:14:15.000Z'
    //       example 2: Truncate('2026-03-03T13:14:15.999Z', 1000).toISOString()
    //       returns 2: '2026-03-03T13:14:15.000Z'
    //       example 3: Truncate('2026-03-03T13:14:44.900Z', 60000).toISOString()
    //       returns 3: '2026-03-03T13:14:00.000Z'
    const date = toTimeDate(value);
    const unit = Number(unitMs);
    if (!Number.isFinite(unit) || unit <= 0) {
        throw new TypeError('Truncate(): invalid unit');
    }
    return new Date(Math.trunc(date.getTime() / unit) * unit);
}