this can be done more generically:

<template>
    <q-input
        v-model="who"
        label="Who"
        dense
        @focus="selectOnFocus"
        @keyup.enter="focusOnSubmit"
      />
</template>

<script>
//using composition API
// ...
setup (props) {
    const data = reactive({
      your: 'Data',
      goes: 'Here',
    })
    const dataRefs = toRefs(data)

    const selectOnFocus = (fEv) => fEv.target.select()
    return {selectOnFocus, ...dataRefs }
  },
// ...

this can be done more generically:

<template>
    <q-input
        v-model="who"
        label="Who"
        dense
        @focus="selectOnFocus"
        @keyup.enter="focusOnSubmit"
      />
</template>

<script>
//using composition API
// ...
setup (props) {
    const data = reactive({
      your: 'Data',
      goes: 'Here',
    })
    const dataRefs = toRefs(data)

    const selectOnFocus = (fEv) => fEv.target.select()
    return {selectOnFocus, ...dataRefs }
  },
// ...