example.vue

<!-- Parent -->
<template>
  <CommonInput v-model="inputValue" />
</template>

<script setup lang="ts">
import { ref } from "vue";

const inputValue = ref();
</script>


<!-- Child -->
<template>
  <input
    :value="props.modelValue"
    @input="emit('update:modelValue', $event.target.value)"
  />
</template>

<script setup lang="ts">
const props = defineProps(["modelValue"]);
const emit = defineEmits(["update:modelValue"]);
</script>


<!-- **************** With defineModel **************** -->
<!-- https://javascript.plainenglish.io/understanding-vue-3s-definemodel-for-two-way-binding-streamline-your-code-with-this-guide-ac970f365e4a -->
<!-- Parent -->
<template>
  <CommonInput v-model="inputValue" />
</template>

<script setup lang="ts">
import { ref } from "vue";

const inputValue = ref();
</script>


<!-- Child -->
<template>
  <input v-model="model" />
</template>

<script setup lang="ts">
// declares "modelValue" prop, consumed by parent via v-model
const model = defineModel();
// emits "update:modelValue" when mutated
model.value = "hello";
</script>




<!-- **************** Without defineModel **************** -->
<!-- Child -->
<template>
  <input v-model="props.modelValue" />
</template>

<script setup lang="ts">
import { defineProps, defineEmits } from 'vue';

const props = defineProps(["modelValue"]);
const emit = defineEmits(["update:modelValue"]);
</script>


<!-- OR with computed, probably better-->

<!-- Child -->
<template>
  <input v-model="inputValue" />
</template>

<script setup lang="ts">
import { computed } from 'vue';

const props = defineProps(['modelValue']);
const emit = defineEmits(['update:modelValue']);

const inputValue = computed({
  get: () => props.modelValue,
  set: (value) => emit('update:modelValue', value),
});
</script>