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function checkDate(dateString){
    if(!/^\d{4}\/\d{1,2}\/\d{1,2}$/.test(dateString))
        return false;

    var parts = dateString.split("/");
    var year = parseInt(parts[0], 10);
    var month = parseInt(parts[1], 10);
    var day = parseInt(parts[2], 10);
    console.log(parts)

    if(year < 1000 || year > 3000 || month == 0 || month > 12)
        return false;

    var monthLength = [ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 ];

    if(year % 400 == 0 || (year % 100 != 0 && year % 4 == 0))
        monthLength[1] = 29;
    return day > 0 && day <= monthLength[month - 1];
}