Upload files on Angular

mahasiswa.service.ts

updateFile(foto_param)
{
    const formData: FormData = new FormData()
    formData.append('pas_foto', foto_param, foto_param.name);
    return this.http.post(''.concat( this.config.server_url ,"mahasiswas/beasiswa/berkas/", ""+this.user_id), formData);
  }

views.component.html

<tr>
    <td>
        <input type="file" nbInput fullWidth (change)="onPasFotoSelected($event)">
    </td>
</tr>

views.component.ts

onPasFotoSelected(event) {
    if(event.target.files.length > 0) 
     {
      const reader = new FileReader();
      reader.onload = e => this.pas_foto = reader.result;

        reader.onloadend = (e) => {

          this.mahasiswa.updateFile(reader.result).subscribe(
            (data) => {
              console.log(data)
            }
          )

        }

      reader.readAsDataURL(event.target.files[0]);
      this.pas_foto_name = event.target.files[0].name
     }
   }