ES6 random guid generator

get_random_guid.js

var t0 = performance.now();

// 
// @source https://gist.github.com/webolizzer/e521db1b1401080b98f06c46c837be6f
//

function get_random_guid() {

    const POSSIBILITIES_PER_ROUND = 512;

    const UUID_TMPL = 'xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx';

    let Chars = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';

    let get_random_char = () => {

        // we create first a large empty array for random chars

        let PossibilitiesArray = [...Array(POSSIBILITIES_PER_ROUND).keys()];

        // @then we fill this array with random chars
        // @note every aray value is random!

        let MapCb = () => {

            let CharsArray = Chars.split('');

            let RandomChar = CharsArray[Math.floor(Math.random() * CharsArray.length)];

            return RandomChar;

        };

        let RandomCharsArray = PossibilitiesArray.map(MapCb);

        // @then we get a random char from RandomCharsArray

        let RandomChar = RandomCharsArray[Math.floor(Math.random() * RandomCharsArray.length)];

        return RandomChar;

    };

    // @then we replace characters of UUID_TMPL with random chars
    // @note every single replacement will call get_random_char()

    return UUID_TMPL.replace(/[x]/g, () => get_random_char());

}

console.log(get_random_guid());

// 

var t1 = performance.now();

console.log("Call took " + (t1 - t0) + " milliseconds.");