Récupérer la date d'un datepicker en HTML et Javascript

<input type="date" id="date-string" />

    <script>    

        const input = document.querySelector('#date-string');
        input.value = '2021-12-31';

        input.addEventListener('input', () => {
        //console.log(input.value) // 2021-03-31
        window.location.href = "http://127.0.0.1:5500/date.html/"+input.value;
    });

    </script>