source: trip-planner-front/node_modules/pretty-bytes/index.js@ eed0bf8

'use strict';

const BYTE_UNITS = [
        'B',
        'kB',
        'MB',
        'GB',
        'TB',
        'PB',
        'EB',
        'ZB',
        'YB'
];

const BIBYTE_UNITS = [
        'B',
        'kiB',
        'MiB',
        'GiB',
        'TiB',
        'PiB',
        'EiB',
        'ZiB',
        'YiB'
];

const BIT_UNITS = [
        'b',
        'kbit',
        'Mbit',
        'Gbit',
        'Tbit',
        'Pbit',
        'Ebit',
        'Zbit',
        'Ybit'
];

const BIBIT_UNITS = [
        'b',
        'kibit',
        'Mibit',
        'Gibit',
        'Tibit',
        'Pibit',
        'Eibit',
        'Zibit',
        'Yibit'
];

/*
Formats the given number using `Number#toLocaleString`.
- If locale is a string, the value is expected to be a locale-key (for example: `de`).
- If locale is true, the system default locale is used for translation.
- If no value for locale is specified, the number is returned unmodified.
*/
const toLocaleString = (number, locale, options) => {
        let result = number;
        if (typeof locale === 'string' || Array.isArray(locale)) {
                result = number.toLocaleString(locale, options);
        } else if (locale === true || options !== undefined) {
                result = number.toLocaleString(undefined, options);
        }

        return result;
};

module.exports = (number, options) => {
        if (!Number.isFinite(number)) {
                throw new TypeError(`Expected a finite number, got ${typeof number}: ${number}`);
        }

        options = Object.assign({bits: false, binary: false}, options);

        const UNITS = options.bits ?
                (options.binary ? BIBIT_UNITS : BIT_UNITS) :
                (options.binary ? BIBYTE_UNITS : BYTE_UNITS);

        if (options.signed && number === 0) {
                return ` 0 ${UNITS[0]}`;
        }

        const isNegative = number < 0;
        const prefix = isNegative ? '-' : (options.signed ? '+' : '');

        if (isNegative) {
                number = -number;
        }

        let localeOptions;

        if (options.minimumFractionDigits !== undefined) {
                localeOptions = {minimumFractionDigits: options.minimumFractionDigits};
        }

        if (options.maximumFractionDigits !== undefined) {
                localeOptions = Object.assign({maximumFractionDigits: options.maximumFractionDigits}, localeOptions);
        }

        if (number < 1) {
                const numberString = toLocaleString(number, options.locale, localeOptions);
                return prefix + numberString + ' ' + UNITS[0];
        }

        const exponent = Math.min(Math.floor(options.binary ? Math.log(number) / Math.log(1024) : Math.log10(number) / 3), UNITS.length - 1);
        // eslint-disable-next-line unicorn/prefer-exponentiation-operator
        number /= Math.pow(options.binary ? 1024 : 1000, exponent);

        if (!localeOptions) {
                number = number.toPrecision(3);
        }

        const numberString = toLocaleString(Number(number), options.locale, localeOptions);

        const unit = UNITS[exponent];

        return prefix + numberString + ' ' + unit;
};