JSON

var str = '{"foo": "bar", "baz": [20, 30]}';

var obj1 = JSON.parse(str);
var obj2 = eval("(" + str + ")");
var obj3 = {"foo": "bar", "baz": [20, 30]};

var obj4 = {};
obj4.foo = "bar";
obj4.baz = [20, 30];

console.log(obj1.foo == obj2.foo, obj2.foo == obj3.foo, obj3.foo == obj4.foo, obj4.foo == "bar"); // true true true true