function checkFileType(type, file, back) {
    var args = arguments;
    if (args.length != 3) {
      back(0);
    }
    var type = args[0]; // type = '(png|jpg)' , 'png'
    var file = args[1];
    var back = typeof args[2] == 'function' ? args[2] : function () {};
    if (file.type == '') {
      // 如果系统无法获取文件类型，则读取二进制流，对二进制进行解析文件类型
      var imgType = [
        'ff d8 ff', //jpg
        '89 50 4e', //png
        '0 0 0 14 66 74 79 70 69 73 6F 6D', //mp4
        '0 0 0 18 66 74 79 70 33 67 70 35', //mp4
        '0 0 0 0 66 74 79 70 33 67 70 35', //mp4
        '0 0 0 0 66 74 79 70 4D 53 4E 56', //mp4
        '0 0 0 0 66 74 79 70 69 73 6F 6D', //mp4
        '0 0 0 18 66 74 79 70 6D 70 34 32', //m4v
        '0 0 0 0 66 74 79 70 6D 70 34 32', //m4v
        '0 0 0 14 66 74 79 70 71 74 20 20', //mov
        '0 0 0 0 66 74 79 70 71 74 20 20', //mov
        '0 0 0 0 6D 6F 6F 76', //mov
        '4F 67 67 53 0 02', //ogg
        '1A 45 DF A3', //ogg
      ];
      var typeName = [
        'jpg',
        'png',
        'mp4',
        'mp4',
        'mp4',
        'mp4',
        'mp4',
        'm4v',
        'm4v',
        'mov',
        'mov',
        'mov',
        'ogg',
        'ogg',
      ];
      var sliceSize = /png|jpg|jpeg/.test(type) ? 3 : 12;
      var reader = new FileReader();
      reader.readAsArrayBuffer(file);
      reader.addEventListener("load", function (e) {
        var slice = e.target.result.slice(0, sliceSize);
        reader = null;
        if (slice && slice.byteLength == sliceSize) {
          var view = new Uint8Array(slice);
          var arr = [];
          view.forEach(function (v) {
            arr.push(v.toString(16));
          });
          view = null;
          console.log(arr.join(' '));
          var idx = arr.join(' ').indexOf(imgType);
          if (idx > -1) {
            back(typeName[idx]);
            console.log(typeName[idx]);
          } else {
            back(false);
          }
        } else {
          back(false);
        }
      });
    } else {
      var type = file.name.match(/\\.(\\w+)$/)[1];
      back(type);
    }
  }

  input.addEventListener(function () {
    var file = this.files[0];
    if (file.type == '') {
      // 第一个参数支持单类型，或多类型，多类型时用竖线分隔，用于生成正则式
      checkFileType('(png|jpg|jpeg|mp4|mov|m4v|ogg)', file, function (fileType) {
        console.log(fileType);
        //'png'
      });
      checkFileType('jpg', file, function (fileType) {
        console.log(fileType);
        //false
      });
    }
  });