JavaScript Unique ID Generate

<script type="text/javascript">
    var uniqueId = Date.now() + Math.floor(Math.random() * 1000);

        function generateUUID() {
            return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
                let r = Math.random() * 16 | 0;
                let v = c === 'x' ? r : (r & 0x3 | 0x8);
                return v.toString(16);
            });
        }
</script>