code: function toBuffer(arrayBuffer) {
      if (Array.isArray(arrayBuffer)) {
          return new Buffer(arrayBuffer);
      }
      else {
          var length = arrayBuffer.byteLength;
          var view = new DataView(arrayBuffer, 0, length);
          var buffer = new Buffer(length);
          for (var i = 0, l = length; i < l; i++) {
              buffer[i] = view.getUint8(i, false);
          }
      }
  
      return buffer;
  }
docs: ArrayBuffer转换成Buffer
  
  @param {ArrayBuffer} arrayBuffer 缓冲数组
  @return {Buffer}