/^[京津滬渝冀豫雲遼黑湘皖魯新蘇浙贛鄂桂甘晉蒙陝吉閩貴



function isVehicleNumber(vehicleNumber) {
      var express = /^[京津滬渝冀豫雲遼黑湘皖魯新蘇浙贛鄂桂甘晉蒙陝吉閩貴粵青藏川寧瓊使領A-Z]{1}[A-Z]{1}[警京津滬渝冀豫雲遼黑湘皖魯新蘇浙贛鄂桂甘晉蒙陝吉閩貴粵青藏川寧瓊]{0,1}[A-Z0-9]{4}[A-Z0-9掛學警港澳]{1}$/;
      return express.test(vehicleNumber);
  }