https://github.com/kapouer/bytes.js

bytes.js

//adapted from https://github.com/kapouer/bytes.js

var util = util || {};
(function (util) {
    function bytes(size) {
        if ('number' == typeof size) return convert(size);
        var parts = size.match(/^(\d+(?:\.\d+)?) *(kb|mb|gb)$/i),
            n = parseFloat(parts[1]),
            type = parts[2].toLowerCase();
        var map = {
            kb: 1 << 10,
            mb: 1 << 20,
            gb: 1 << 30
        };
        return map[type] * n;
        /**
         * convert bytes into string.
         *
         * @param {Number} b - bytes to convert
         * @return {String}
         * @api public
         */
        function convert(b) {
            var gb = 1 << 30,
                mb = 1 << 20,
                kb = 1 << 10;
            if (b >= gb) return (Math.round(b / gb * 100) / 100) + 'GB';
            if (b >= mb) return (Math.round(b / mb * 100) / 100) + 'MB';
            if (b >= kb) return (Math.round(b / kb * 100) / 100) + 'KB';
            return b + 'B';
        }
    };
    util.bytes = bytes;
})(util);

test.js

util.bytes(1024* 1024 * 1.5) // => 1.5MB