Custom Client Side Formatters Issue

Hello @Teodor ,
I need add new client side formatter .

dmx.Formatters('string', {
    encodeBase64: btoa,
    decodeBase64: atob
});

usage ;

{{'Hello world'.encodeBase64()}} or {{testData.encodeBase64()}}

returned result ;

client.jpg701×396 50.9 KB

how can I fix this issue ?