const datePicker = document.getElementById("date-picker");

datePicker.min = getDate();
datePicker.max = getDate(14);

// Borrowed from https://stackoverflow.com/a/29774197/7290573
function getDate(days) {
    let date;

    if (days !== undefined) {
        date = new Date(Date.now() + days * 24 * 60 * 60 * 1000);
    } else {
        date = new Date();
    }

    const offset = date.getTimezoneOffset();

    date = new Date(date.getTime() - (offset*60*1000));

    return date.toISOString().split("T")[0];
}

<input id="date-picker" type="date" autocomplete="off" />