JSFiddle - React, Tailwind, and code Playground

HTML

<div id="output">
</div>

JavaScript

var UUID = function (binaryData, offset) {
    var data1 = binaryData.slice(offset + 0, offset + 4);
    var data2 = binaryData.slice(offset + 4, offset + 6);
    var data3 = binaryData.slice(offset + 6, offset + 8);
    var data4 = binaryData.slice(offset + 8, offset + 16);

    data1 = swap32(data1);
    data2 = swap16(data2);
    data3 = swap16(data3);

    this.string
        = data1.toString(32) + '-'
        + data2.toString(16) + '-'
        + data3.toString(16) + '-'
        + data4.toString();

    this.data_length = 16;
};

function swap32(src) {
    return (
        ((src & 0xFF000000) >> 24) |
        ((src & 0x00FF0000) >> 8) |
        ((src & 0x0000FF00) << 8) |
        ((src & 0x000000FF) << 24)
    );
}

function swap16(src) {
    return (
        ((src & 0xff00) >> 8) |
        ((src & 0x00ff) << 8)
    );
}

var testData = swap16(512);

document.getElementById('output').innerHTML = printIt(testData);