js transform function

transform.js

function Test() {
 this.data = {
   "foo":"bar"
 };
}

Test.prototype.transform = function(str) {
  
  var err = false;
  var input = this.data;
  var output = false;
  
  try {
    function run() {
      eval(str);
      return output;
    }
    output = run();
  }catch(e) {
    err = e;
  }
  
  
  console.log((err)?err:output);
  
  //console.log(this.data);
  
}

var a = new Test();

a.transform('output = input');