Jquery Serialize not working to post to laravel controller

Use save() instead of update;

$k->nama = $request->nama;
$k->telp = $request->telp;
$k->bagian = $request->bagian;
$k->nik_lama = $request->nik_lama;
$k->nik_baru = $request->nik_baru;
$k->jk = $request->jk;
$k->alamat = $request->alamat;
$k->save();

I recommend use the update method with an array.

karyawan::find($id)->update([
  'nama' => $request->nama,
  'telp' => $request->telp;
  'bagian' => $request->bagian;
  'nik_lama' => $request->nik_lama;
  'nik_baru' => $request->nik_baru;
  'jk' => $request->jk;
  'alamat' => $request->alamat;
]);

Make sure all fields are fillable in your model.

One more way to update is

karyawan::find($id)->update($request->all());