您可以使用file readerHTML5

中的JavaScript读取本地文件：http

//www.html5rocks.com/en/tutorials/file/dndfiles/

    function handleFileSelect(evt) {
      var files = evt.target.files; // FileList object

      // files is a FileList of File objects. List some properties.
      var output = [];
      for (var i = 0, f; f = files[i]; i++) {
        console.log(f.size);        /*<--Here is your size of the file! :D*/
      }
    }

    document.getElementById('files').addEventListener('change', handleFileSelect, false);