input to the image into base64 format

var file = this.files[0];//this是监听的file input
//var file = e.target.files.item(0);//Vue这么获取

if (window.FileReader) {
      var reader = new FileReader();
      reader.readAsDataURL(file);
      //监听文件读取结束后事件
      reader.onloadend = function(e) {
      	console.log(e.target.result);
          //Vue.set(app, "img", e.target.result);
      };
  }