# Class names type safety

It's like [clsx](https://www.npmjs.com/package/clsx) but you can only pass it classes that are from the dsfr.

<figure><img src="/files/NzVU6UyzijGQq43hm1tb" alt=""><figcaption></figcaption></figure>

You can't apply your custom classes using fr.cx(), you'll get type error, but you can combine a regular `cx()` or `clsx()` function and `fr.cx()`. Example:

```tsx
import { useStyles } from "tss-react/dsfr";
import { fr } from "@codegouvfr/react-dsfr";  

type Params = {
    className?: string;
};

export function MyComponent(params: Params){

   const { className } = params;  
   
   const { cx } = useStyles();
   
   return (
       <div className={cx(fr.cx("fr-p-10v"), className)}>
           //...
       </div>
   );

}
```


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