code: function checkSum(buffer, offset, length) {
              if (buffer instanceof ArrayBuffer) {
                  return checkSumArrayBuffer(buffer, offset, length);
              }
              else if (buffer instanceof Array) {
                  return checkSumArray(buffer, offset, length);
              }
  
              throw new Error('not support checksum buffer type');
          }
docs: table校验
  
  @param {ArrayBuffer|Array} buffer 表数据
  @param {number=} offset 偏移量
  @param {number=} length 长度
  
  @return {number} 校验和