Code snippet for Angular2 typescript to convert file to Blob64 encoded string

blob64_snippet.ts

  onFileChange(event){
    let files = event.srcElement.files;
    this.selectedFile = files[0];
    if (files && this.selectedFile) {
        let reader = new FileReader();
        reader.onload = this._handleReaderLoaded.bind(this);
        reader.readAsBinaryString(this.selectedFile);
    }
  }

  _handleReaderLoaded(readerEvt) {
    var binaryString = readerEvt.target.result;
    this.selectedFileAsBase64String = btoa(binaryString);
    console.log(btoa(binaryString));
  }