仅显示日期字符串中的日期和月份

function extractDateAndMonth(dateString) {
  // 获取日期部分
  var dateSeparatorIndex = dateString.indexOf("-");
  var date = dateString.substring(dateSeparatorIndex + 1, dateSeparatorIndex + 3);

  // 获取月份部分
  var monthSeparatorIndex = dateString.lastIndexOf("-");
  var month = dateString.substring(monthSeparatorIndex + 1, monthSeparatorIndex + 3);

  return {
    date: date,
    month: month
  };
}

var dateString = "2022-12-31";
var result = extractDateAndMonth(dateString);
console.log(result.date);  // 输出：31
console.log(result.month); // 输出：12

function extractDateAndMonth(dateString) {
  var regex = /(\d{2})-(\d{2})/;
  var match = regex.exec(dateString);

  if (match) {
    var date = match[1];
    var month = match[2];

    return {
      date: date,
      month: month
    };
  }

  return null;
}

var dateString = "2022-12-31";
var result = extractDateAndMonth(dateString);
console.log(result.date);  // 输出：31
console.log(result.month); // 输出：12