Question

On JSON.org the essential data structures that JSON represents are given as

1. A collection of name/value pairs, and
2. An ordered list of values.

I have not been able to find anywhere whether a second member having the same name as one already parsed into the current object should (a) throw an exception or (b) replace the existing member.

Is this specified anywhere?

What do existing parsers do with repeated names?

EDIT: I am looking to define correct behavior for my parser.

Answer 1

JSON is simply a subset of the object literal notation of JavaScript and as such, is constrained by the same rules – the latest value for repeated keys will override any previously assigned value for that key, within the specific object. Think in terms of assigning a value to an object property; A later assignment will override an earlier one.

To demonstrate this, I have set up an example here. The code is displayed on the page, and as can be seen, the messagebox has the name ‘Barney’ in it.

Code here –

$(function() {      $('#myButton').click(function(e)       {      var myJsonString =  'Person = {'firstName':'Fred','lastName':'Flintstone','firstName':'Barney'}';      eval('(' + myJsonString + ')');      alert(Person.firstName);      });  }); 

By the Way, I have used eval() here for ease of use. I would recommend using a JSON parser instead of eval() due to security issues.