What is wrong with this "replace"?

There must be some typo in here, but I am not seeing it. Anyone else knows what is wrong?
<select id="inp_onderdeel" class="form-control" name="onderdeel" dmx-bind:value="updatefill.data.query1[0].onderdeel.toNumber().toString().replace(2, 'Bestuur').replace(3, 'RvT')">