How to use Prepare in React.

[HeisPovedim]

I can't understand the correct syntax of writing on ReactJS.
the guide says to write like this:
prepare: function (str) { return str.toUpperCase(); },
But it doesn't work on recat(

[karandashovrz]

@HeisPovedim Check it out https://codesandbox.io/s/react-imask-input-box-masks-forked-tii4v6?file=/src/index.js
Do you have use prepare handler with setted mask property?