js 日期 nan

function processDate(input) {
    let date;
    if (typeof input === 'string') {
        date = new Date(input);
    } else if (typeof input === 'number') {
        date = new Date(input);
    } else {
        return "Invalid input type";
    }

    if (isNaN(date.getTime())) {
        return "Invalid date";
    }

    return date.toISOString();
}

console.log(processDate("2023-10-05")); // "2023-10-05T00:00:00.000Z"
console.log(processDate("abc")); // "Invalid date"
console.log(processDate(1633430400000)); // "2021-10-05T00:00:00.000Z"
console.log(processDate(null)); // "Invalid input type"