focus last after fields.push() not possible, because no possibility to focus on callback

Hello, I have 1 suggestion, when I push value, can't focus new element, because it is not created yet

```javascript
fields.push({id: '', name: '', lastName: ''})
setTimeout(()=>{
form.focus(`persons[${fields.value.length}].id`)
},200)
```

this is how it works now, but obviously, its really bad solution, if fields.push had a callback, it would be nice

just wondering, why fields.push acts like async?

The issue provides no file or test names. Start by locating the fields.push entry point and tracing when the new array field is created, then review the surrounding API and lifecycle behavior before deciding how a callback could be supported. Done should allow callers to focus the new field without relying on setTimeout, with tests covering the resulting behavior.

Written by the indexing model from the issue text.