```js
valeurs_d = "";
for (var i = 0; i < keys.length -1 ; i++)
valeurs_d += + event[keys[i]] + ", ";
var str5 = ",";
var str6 = str5.concat(valeurs_d);
var valeurs = str6.substring (0, str6.length - 2);
console.log(valeurs);
```

I have a json document like this :

```js
 {
  "temperature" : 12.45,
  "lala" : 45.75,
  "humidite" : 45.78,
  "toto" : "gvvgvh",
  "topic" : "sk1_001/data"
 }
```

The problem when I retrieve the values. I have the following result: 12.45, 45.75, 45.78, NaN!

I want to retrieve my string instead of NaN, How ?

edit : Thank you, it's donne, but I hava annoter question :

Typeof in Javascript returns number or string, or I want to return varchar for string, and double for number.

I need this to write on my Apache Cassandra database in node.js.

How can I proceed to return varchar and double ?