Conver file to base64 and upload

Avatar.tsx

const uploadHandler = (e: ChangeEvent<HTMLInputElement>) => {
        if (e.target.files && e.target.files.length) {
            const file = e.target.files[0]
            if (file.size < 4000000) {
                convertFileToBase64(file, (file64: string) => {
                    dispatch(updateProfileTC({avatar: file64}))
                })
            } else {
                dispatch(setAppErrorAC('Файл слишком большого размера'))
            }
        }
    }


// https://stackoverflow.com/a/20285053 js
// https://stackoverflow.com/a/47177899 react
const convertFileToBase64 = (file: File, callBack: (value: string) => void) => {
        // https://developer.mozilla.org/ru/docs/Web/API/FileReader/FileReader
        const reader = new FileReader();

        // https://developer.mozilla.org/ru/docs/Web/API/FileReader/readAsDataURL
        reader.onloadend = () => {
            const file64 = reader.result as string
            callBack(file64)
        }
        reader.readAsDataURL(file)
    }