how to access then response outside promise in node using imageToBase64

Question

I am using this npm package to output a base64 format of an uploaded picture and it is working just fine:

    imageToBase64("./upload/image.png").then(
    (response) => {
        console.log("Then",response);
    }
).catch(
    (error) => {
        console.log("catch",error);
    }
   
)

My problem is how can I get the response data from that promise and add that into an node object.