const PRName = function () { let ID = ''; // let characters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; const characters = '0123456789'; for ( let i = 0; i < 6; i++ ) { ID += characters.charAt(Math.floor(Math.random() * 10)); } return 'PR-'+ID; }; console.log(PRName());