var characters="0123456789abcdefghijklmnopqrstuvwxyz"
var stringlength=16
var myRand = ""
var n = 0
var randomnumber = 0
while( n < stringlength ) {
   n ++
   randomnumber = Math.floor(characters.length*Math.random());
   myRand += characters.substring(randomnumber,randomnumber + 1)
}