JS ALPHANUMERIC Random Letter Shifting Cipher Algorithm FIN

<script>
var possible = "FABCGDEGHIJKLMNOP0QRSTUVWXYZ";
var text = "";

for(var i=0; i<26; i++){
text+=possible.charAt(Math.floor(Math.random()*possible.length))

document.writeln('<br>\n\n'+text+'\n');
document.writeln("ABCDEFGHIJKLMNOPQRSTUVWXYZ\n");
text='';
}
</script>