How to access nested JSON data

To be honest, I can't understand your problem. JSON is already structured out, why do you need to change the structure?

In you case, I would access it as follows:

data.address.streetName;

If, by any chance, what you want is to traverse the data, you would need:

function traverse_it(obj){
    for(var prop in obj){
        if(typeof obj[prop]=='object'){
            // object
            traverse_it(obj[prop[i]]);
        }else{
            // something else
            alert('The value of '+prop+' is '+obj[prop]+'.');
        }
    }
}

traverse_it(data);

---

Update

After reading below, what this user needs seems more obvious. Given property names as a string, s/he wants to access the object.

function findProp(obj, prop, defval){
    if (typeof defval == 'undefined') defval = null;
    prop = prop.split('.');
    for (var i = 0; i < prop.length; i++) {
        if(typeof obj[prop[i]] == 'undefined')
            return defval;
        obj = obj[prop[i]];
    }
    return obj;
}

var data = {"id":1,"name":"abc","address":{"streetName":"cde","streetId":2}};
var props = 'address.streetName';
alert('The value of ' + props + ' is ' + findProp(data, props));

If you use lodash(a very popular utility library), you can use _.get().

e.g.

var data = {
  "id":1,
  "name": "abc",
  "address": {
    "streetName": "cde",
    "streetId":2
  }
}
_.get(data, 'address.streetName');
// 'cde'
_.get(data, ['address', 'streetName']);
// 'cde'

If it involves an array, you can use string path like 'address[0].streetName' as well.

e.g.

var data = {
  "id":1,
  "name": "abc",
  "addresses": [
    {
      "streetName": "cde",
      "streetId": 2
    },
    {
      "streetName": "xyz",
      "streetId": 102
    },
  ]
}
_.get(data, 'addresses[0].streetName');
// cde
_.get(data, [address, 1, streetName]);
// xyz

Internally, it uses toPath() function to convert string path (e.g. address.streetName) into an array (e.g. ['address', 'streetName']), and then uses a function to access the data at the given path within the object.

Other similar utility functions include _.set() and _.has(). Check them out.