This is a simple function which can be called to fetch value for any unique key in simple or complex json object.

Example:

var obj = {"name":"Chris","age":23,"address":{"city":"New York","country":"America"},"friends":[{"name":"Emily","hobbies":["biking","music","gaming"]},{"name":"John","hobbies":["soccer","gaming"]}]};
var val = getKeyValue(obj, 'city');
gs.info(val);

// this function takes the complete json object and the unique key whose value needs to be fetched
function getKeyValue(obj, key){
try {
            if (obj.hasOwnProperty(key)) {
                return obj[key];
            }
            for (var k in obj) {
                if (typeof obj[k] === 'object' && obj[k] !== null) {
                    var result = this.getKeyValue(obj[k], key);
                    if (result !== undefined) {
                        return result;
                    }
                }
            }
            return undefined;
        } catch (ex) {
            gs.info("Exception in function getKeyValue " + ex);
        }
}

Output: