FileReader.onload 从未在角度中触发

Question

我有以下几行代码。我昨天让它工作了，但今天 reader.onload 事件从未被调用，这导致无法进入该函数。知道这是怎么发生的或者为什么它没有被触发吗？

fileChange(event) {
    let fileList: FileList = event.target.files;
    var file = fileList[0];
    var reader = new FileReader();
    reader.onload = this._handleReaderLoaded.bind(this);
    }

    _handleReaderLoaded(readerEvt) {
      var binaryString = readerEvt.target.result;
      this.base64textString= btoa(binaryString);
      console.log(btoa(binaryString));
      this.photo.image = this.image;
      this.photo.title = 'test';
      this.photo.image.data = btoa(binaryString);
      this.formData.sessionPhoto = this.photo;
    }

Answer 1

您忘记读取文件：

reader.readAsArrayBuffer(file);

fileChange(event) {
    let fileList: FileList = event.target.files;
    var file = fileList[0];
    var reader = new FileReader();
    reader.onload = this._handleReaderLoaded.bind(this);
    reader.readAsArrayBuffer(file);
}