我想出了这个：

function isValidDate(inputDate){

    var myRegex = /^(\d{1,2})([\-\/])(\d{1,2})\2(\d{4}|\d{2})$/;
    var match = myRegex.exec(inputDate);

    if (match != null) {
        var auxDay = match[1];
        var auxMonth = match[3] - 1;
        var auxYear = match[4];
        auxYear = auxYear.length < 3 ? (auxYear < 70 ? '20' + auxYear : '19' + auxYear) : auxYear;
        var testingDate = new Date(auxYear,auxMonth,auxDay);
        return ((auxDay == testingDate.getDate()) && (auxMonth == testingDate.getMonth()) && (auxYear == testingDate.getFullYear()));
    } else return false;
}

适用于dd-mm-yyyy，dd-mm-yy，d-m-yyyy和d-m-yy，使用-或/作为分隔符