How to remove "NULL" strings from a JSON object in sails.js using Javascript?

The JSON Object is as shown below. I want to remove all the keys with the value NULL. Also, if after removing the pair, if the entry is blank then that should also be removed. I have tried looking for a script that performs the required task but I haven't been successful at it. Keep in mind, it is a NULL string and not an object. I need to implement this is sails.js so Javascript is the most preferred language.

var JSONobj ={  "regex_attributes": {
"matching attributes": {
  "transaction_amount": {
    "matching_position": "1"
  },
  "total_amount_due": {
    "matching_position": "NULL"
  },
  "transaction_date": {
    "matching_position": "NULL",
    "date_format": "NULL"
  },
  "current_credit": {
    "matching_position": "NULL"
  },
  "available_credit": {
    "matching_position": "NULL"
  },
  "date_posted": {
    "matching_position": "NULL",
    "date_format": "NULL"
  },
  "merchant": {
    "matching_position": "NULL"
  },
  "bill_date": {
    "matching_position": "NULL",
    "date_format": "NULL"
  },
  "bill_due_date": {
    "matching_position": "NULL",
    "date_format": "NULL"
  },
  "bill_amount": {
    "matching_position": "NULL"
  },
  "account_number_ending": {
    "matching_position": "2"
  },
  "balance_date": {
    "matching_position": "NULL",
    "date_format": "NULL"
  },
  "available_balance": {
    "matching_position": "NULL"
  }
},
"additional_processing": [     //Array
  {
    "sms_sender_name": "NULL",
    "type_of_account_to_find": "NULL",
    "attribute": "description",
    "operation": "pre_add",
    "pre_add_1": "Credit"
  }
],
"account_details": {
  "credit_or_debit": "CREDIT",
  "type_of_transaction": "INT",
  "type_of_account": "SAVINGS",
  "type_of_action": "TRANSACTION",
  "bills_account_type": "NULL"
}

} }