JSFiddle - React, Tailwind, and code Playground

HTML

<html>
<head>


</head>
<body>

</body>
</html>

JavaScript

function generateSerial(len) {
    var chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXTZabcdefghiklmnopqrstuvwxyz";
    var string_length = 10;
    var randomstring = '';

    for (var x=0;x<string_length;x++) {

        var letterOrNumber = Math.floor(Math.random() * 2);
        if (letterOrNumber == 0) {
            var newNum = Math.floor(Math.random() * 9);
            randomstring += newNum;
        } else {
            var rnum = Math.floor(Math.random() * chars.length);
            randomstring += chars.substring(rnum,rnum+1);
        }

    }
    alert(randomstring);
}
generateSerial(8);