如何中止/取消文件读取 - FileReader

I'm using this code:

我正在使用此代码：

document.getElementById("fileToUpload").onchange = function () {
  var reader = new FileReader();

  reader.onload = function (e) {
    // get loaded data and render thumbnail.
    $("#image").show();
    document.getElementById("image").src = e.target.result;
  };

  // read the image file as a data URL.
  reader.readAsDataURL(this.files[0]);
};
document.get