I have an input field that gets replaced automatically with a textarea and same content depending on the number of characters the user has entered:
<textarea v-if="myString.length > 20" v-model="myString"/>
<input type="text" v-if="myString.length <= 20" v-model="myString"/>
The problem i have is that the focus gets lost when a user enters the 21st character. And thus the user gets irritated because when he types the 22nd character it does not appear in the textarea (no focus). How can i set the focus on the newly rendered textarea then? Problem here is that it gets rendered automatically. Otherwise i could set a ref on the textarea and call focus().
Another issue is the removal of the 21st character and the switch-back from textarea to the input elment.
(copy from my comment because this might be helpful)
Replacing an input element by a textarea is likely to create a horrible UX. Why don't you just use textarea from the beginning? If you want the style to change based on the input length, e.g. increase the height if there are > 20 characters, then you can use CSS to do that.
<script setup>
const props = defineProps({
modelValue: String,
})
</script>
<template>
<textarea
:value="modelValue"
@input="$emit('update:modelValue', $event.target.value)"
:rows="1"
:style="modelValue.length > 20 ? { minHeight: '100px' } : { minHeight: '0px' }"
/>
</template>
<AutoFocusedInput v-model="myString" />
demo (forked from @tony19)
You could wrap the textarea/input in a component, and use its mounted hook to call its focus(), as seen in this component:
<!-- AutoFocusedInput.vue -->
<script setup>
import { ref, onMounted, computed, nextTick } from 'vue'
const input = ref()
onMounted(async () => {
await nextTick()
input.value.focus()
})
const props = defineProps({
modelValue: String,
textarea: Boolean,
})
const comp = computed(() => (props.textarea ? 'textarea' : 'input'))
</script>
<template>
<component
:is="comp"
ref="input"
v-bind="$attrs"
:value="modelValue"
@input="$emit('update:modelValue', $event.target.value)"
/>
</template>
<AutoFocusedInput textarea v-if="myString.length > 20" v-model="myString" />
<AutoFocusedInput v-else v-model="myString" />
While this is technically possible, this UX is probably not ideal, and you should consider other designs that don't require focusing input like this (as indicated by @kien_coi_1997).