Detecting if a file has a byte order mark (BOM) using JavaScript

gistfile1.txt

      var reader = new FileReader();
      reader.onerror = function (err) {
          console.log('Error:', err);
      };
      reader.onload = function (e) {
          var text = reader.result;
          debugger;
          var buf = new Uint8Array(text);
          // check for byte order mark
          // 0xef, 0xbb and 0xbf in hex converts to 239, 187 and 191 in decimal
          if (buf[0] === 239 && buf[1] === 187 && buf[2] === 191) { // check for byte order mark
              console.log('File has byte order mark (BOM)');
          }

      };
      reader.readAsArrayBuffer(file);