JavaScript - parse file size to bytes (input in: B, KB, MB, GB, TB, PB)

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const EXPRESSION = /^\s*(\d+(?:\.\d+)?)\s?(b|kb|mb|gb|tb|pb|bytes?|kilobytes?|megabytes?|gigabytes?|terabytes?|petabytes?)\s*$/i;

const POWERS = {
//  short                 long                         alias
    b:  1,                bytes:     1,                byte:     1,
    kb: 1024,             kilobytes: 1024,             kilobyte: 1024,
    mb: 1048576,          megabytes: 1048576,          megabyte: 1048576,
    gb: 1073741824,       gigabytes: 1073741824,       gigabyte: 1073741824,
    tb: 1099511627776,    terabytes: 1099511627776,    terabyte: 1099511627776,
    pb: 1125899906842624, petabytes: 1125899906842624, petabyte: 1125899906842624
};

const findPower = (unit) => {
    const key = unit.toLowerCase();
    return POWERS[key];
};

const parseSize = (text) => {
    const match = EXPRESSION.exec(text);
    if (match) {
        const value = parseFloat(match[1]);
        const power = findPower(match[2]);
        return Math.round(value * power);
    }
    return NaN;
};


// Usage example:
                                           // IN BYTES:

console.log(parseSize('10.5KB'));          // 10752
console.log(parseSize('10.5MB'));          // 11010048

console.log(parseSize('10.5 kilobytes'));  // 10752
console.log(parseSize('10.5 megabytes'));  // 11010048


// Alternatives:
//
//     1. https://www.npmjs.com/package/bytes   (https://github.com/visionmedia/bytes.js)


// See also:
//
//     1. https://dirask.com/snippets/JavaScript-format-size-in-bytes-to-human-readable-KB-MB-GB-TB-PB-jmLNQp
//     2. https://dirask.com/snippets/JavaScript-format-size-in-bytes-to-human-readable-KB-MB-GB-TB-PB-jvJOXj
//     3. https://dirask.com/snippets/JavaScript-format-size-in-bytes-to-human-readable-KB-MB-GB-TB-PB-pJa8gD