gistfile1.txt

params = {
    email: data.email,
    "list_id": xxxx,
    "first_name": data.firstName,
    "last_name": data.lastName,
    "$source": source[type],
    "$fields": '$consent,$source',
    "$consent": "web",
}
            
const urlData = new URLSearchParams(params)
fetch(`https://manage.kmail-lists.com/ajax/subscriptions/subscribe`, {
    method: 'POST',
    body: urlData,
})
.then(async response => {
    setSuccess(true)
})
.catch(error => {
    setError('root', {
        type: 'submit',
        error.message,
    })
});