JSFiddle - React, Tailwind, and code Playground

HTML

<body>
    <div class="form-row">
        <!--<label for="field-email">Email*</label>-->
        <input placeholder="Email*" value="" type="email" name="email" required id="field-email" data-error="Wpisz poprawny email"
            pattern="[^@\s]+@[^@\s]+\.[^@\s]+">
    </div>
    <div class="form-row">
        <!--<label for="field-tel">nr. telefonu</label>-->
        <input placeholder="Numer telefonu" value="" type="number" pattern="\d*" name="tel" id="field-tel">
    </div>
    </div>
    <div class="form-row ">
        <!--<label for="field-message">Wiadomość*</label>-->
        <textarea placeholder="Wiadomość*" name="message" required data-error="Musisz wypełnić pole" id="field-message"
            pattern=".+"></textarea>
    </div>
    <div class="form-row">
        <label class="checkbox-cnt">
            <input type="checkbox" required data-error="Musisz wypełnić pole" id="regulation" name="regulation">
            <i class="state" aria-hidden="true"></i>
            <span class="zgoda">*Wyrażam zgodę na przetwarzanie danych osobowych </span>
        </label>
    </div>
    <div class="form-row">
    <label class="checkbox-cnt">
            <input type="checkbox" name="regulationPrezentacja">
            <i class="state" aria-hidden="true"></i>
            <span>darmową prezentację produktów</span>
        </label>
    </div>
    <div class="form-row">
        <label class="checkbox-cnt">
            <input type="checkbox"  name="regulationCennik">
            <i class="state" aria-hidden="true"></i>
            <span>informacje nt. cennika naszych produktów</span>
        </label>
    </div> 
    <div class="form-row">
        <label class="checkbox-cnt">
            <input type="checkbox" name="regulationSpotankie">
            <i class="state" aria-hidden="true"></i>
            <span>kontak w celu umówienia spotkania</span>
        </label>
    </div>
    <br>
    <div style="cursor:pointer;" id="wyslij">Wyslij</div>

</body>

JavaScript

{
        document.querySelector('#wyslij').addEventListener('click', function () {

            const elements = document.querySelector("body").querySelectorAll('input:not(:disabled), textarea:not(:disabled), select:not(:disabled)');
           // console.log(elements);
            const dataToSend = new FormData();

            //[...elements].forEach(el => dataToSend.append(el.name, el.value));

           elements.forEach(function(el) {
                if (el.type=='checkbox'){
                    if (el.checked==true){
                        dataToSend.append(el.name, "Tak");
                    } else {
                        dataToSend.append(el.name, "Nie");
                    }
                    console.log(el.name+" "+el.checked)
                    
                } else {
                    dataToSend.append(el.name, el.value);
                    console.log(el.name+" "+el.value)
                }
                
           });
        });
    }