Question

Why is the result {"a":"b","c":1}?

var foo = {"a":"b","c":0};
var bar = foo;
bar.c++;
alert(JSON.stringify(foo));

How to disable this behavior?

Answer 1

What you’re doing is making a second reference to an object but what it seems you want is a copy of that object instead.

If you want that functionality then you really want a copy function that copies all of the properties, one by one, into a new object:

// Take all the properties of 'obj' and copy them to a new object,
// then return that object
function copy(obj) {
  var a = {};
  for (var x in obj) a[x] = obj[x];
  return a;
}

var foo = {"a":"b","c":0};
var bar = copy(foo);
bar.c++;
alert(JSON.stringify(foo));

and you’ll get {"a":"b","c":0}