如果你想追求正确性，如果你使用JavaScript的Date API，你可以做一个更正确的日期验证。例如：

function validateExpiry (input) {
  // ensure basic format is correct
  if (input.match(/^((0[1-9]|1[0-2])\/\d{2})$/)) {
    const {0: month, 1: year} = input.split("/");

    // get midnight of first day of the next month
    const expiry = new Date("20" + year, month);
    const current = new Date();
    
    return expiry.getTime() > current.getTime();
    
  } else return false;
}

console.log("01/32", validateExpiry("01/32"));
console.log("01/19", validateExpiry("04/18"));
console.log("05/18", validateExpiry("05/18"));
console.log("05.18", validateExpiry("05.18"));
console.log("00/23", validateExpiry("00/23"));
console.log("invalid", validateExpiry("invalid"));

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