Avoid document.write. By putting each Song Object inside of your Array you can achieve this:
var myArray = [{title:'Song 1 Title', artist:'Song 1 Artist'}, {title:'Song 2 Title', artist:'Song 2 Artist'}, {title:'Song 3 Title', artist:'Song 3 Artist'}];
function getRandomSong(ary){
  return ary[Math.floor(Math.random()*ary.length)];
}
var randomSong = getRandomSong(myArray);
console.log(randomSong.title); console.log(randomSong.artist);
Of course, if you have thousands of songs you'll want to execute something similar Sever Side on your database. In PHP this might look like:
<?php
class Song{
  private $db; public $currentSelection;
  public function __construct($databaseConnection){
    $this->db = $databaseConnection;
    $this->currentSelection = $this->getRandomSong();
  }
  public function getRandomSong(){
    $db = $this->db;
    if($sq = $db->query('SELECT COUNT(*) count FROM songTable')){
      if($sq->num_rows > 0){
        $c = $sq->fetch_object(); $rc = rand(1, $c->count);
        if($rq = $db->query("SELECT * FROM songTable WHERE primaryKey=$rc"){
          if($rq->num_rows > 0){
            return json_encode($rq->fetch_assoc());
          }
          else{
            // no rows
          }
          $rq->free();
        }
        else{
          // connection failure
        }
      } 
      else{
        // no rows
      }
      $sq->free();
    }
    else{
      // connection failure
    }
    return false;
  }
}
$songObj = new Song($databaseConnectionHere);
echo $songObj->currentSelection;
echo $songObj->getRandomSong();
$dataBaseConnectionHere->close();
?>