js json and string conversion

String to object (strJSON stands for json string) 
  var obj = eval(strJSON); 
  var obj = strJSON.parseJSON(); 
  var obj = JSON.parse(strJSON); 
json object to string (obj stands for json object) 
  var str = obj.toJSONString(); 
  var str = JSON.stringify(obj) 
requires the json.js package in addition to eval() (remember)