JSFiddle - React, Tailwind, and code Playground

JavaScript

var numbers = "0123456789";

var chars= "acdefhiklmnoqrstuvwxyz";

var string_length = 3;
var randomstring = '';
var randomstring2 = '';

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

    var letterOrNumber = Math.floor(Math.random() * 2);

        var rnum = Math.floor(Math.random() * chars.length);
        randomstring += chars.substring(rnum,rnum+1);


} for (var y=0;y<string_length;y++) {

    var letterOrNumber2 = Math.floor(Math.random() * 2);

        var rnum2 = Math.floor(Math.random() * numbers.length);
        randomstring2 += numbers.substring(rnum2,rnum2+1);


}
var code=randomstring+randomstring2;
alert(code);