Angular filereader base64 remove preceding data

问题

In Angular, I'm converting blob to base64 FileReader. But I want to remove the data:application/octet-stream;base64, at the start.

  getRecordedAudio() {
    if (this.recordedAudio) {
      let fileReader = new FileReader();    
      fileReader.onloadend = function() {
        let base64data = fileReader.result;
        //base64data = base64data.split(',')[1]; ---> How can this be done?
        console.log('base64data-', base64data);
      };
      fileReader.readAsDataURL(this.recordedAudio);
    }
  }

How can I do this?

I'm getting error:

Property 'split' does not exist on type 'ArrayBuffer'.

来源：https://stackoverflow.com/questions/58473636/angular-filereader-base64-remove-preceding-data