v-model in Vue.js is a syntactic sugar for two-way data binding that combines :value and @input directives, automatically syncing form inputs with component data. 1. For text inputs and textareas, it uses the value property and input event. 2. For checkboxes, it binds to a boolean when single, or to an array when multiple. 3. For radio buttons, it binds to a single value using the change event. 4. For select dropdowns, it syncs the selected option with the bound data. When used on custom components, v-model defaults to modelValue prop and update:modelValue event, but can be customized with argument syntax like v-model:search. It also supports modifiers: .lazy for change event instead of input, .number for automatic type conversion, and .trim to remove whitespace, making it a flexible and efficient tool for form handling.
v-model is Vue.js’s built-in directive for creating two-way data binding on form inputs, checkboxes, selects, and more. It simplifies the process of syncing data between the view (the input field) and the model (your Vue component’s data). Here's how it works under the hood.
What v-model actually does
At its core, v-model is syntactic sugar — a convenient shorthand — for combining two common operations:
- Binding the input’s value to a piece of data (
:value="something") - Listening for input events to update that data (
@input="something = $event.target.value")
So when you write:
<input v-model="message">
It’s essentially the same as writing:
<input :value="message" @input="message = $event.target.value">
This ensures that whenever the user types in the input, the message data property is immediately updated, and if message changes programmatically, the input reflects the new value.
How it works with different elements
v-model behaves slightly differently depending on the type of form element:
1. Text inputs and textareas
Just as shown above — uses value and input event.
<input type="text" v-model="text"> <textarea v-model="text"></textarea>
2. Checkbox inputs
For a single checkbox: binds to a boolean.
<input type="checkbox" v-model="isChecked"> <!-- isChecked will be true or false -->
For multiple checkboxes bound to an array:
<input type="checkbox" v-model="fruits" value="apple"> Apple <input type="checkbox" v-model="fruits" value="banana"> Banana <!-- fruits will be an array like ['apple'] -->
3. Radio buttons
Binds to a single value (string or number), uses value attribute and change event.
<input type="radio" v-model="choice" value="option1"> Option 1 <input type="radio" v-model="choice" value="option2"> Option 2
4. Select dropdowns
Works similarly to text inputs but with selected <option>.
<select v-model="selected"> <option value="a">A</option> <option value="b">B</option> </select>
v-model in components (custom components)
When you use v-model on a custom component, it assumes:
- The component accepts a
modelValueprop (in Vue 3; previouslyvalue) - The component emits an
update:modelValueevent (or usesv-modelwith argument syntax)
You can customize this:
<CustomInput v-model="message" />
Is equivalent to:
<CustomInput :modelValue="message" @update:modelValue="message = $event" />
Inside your CustomInput component:
<script setup>
defineProps(['modelValue'])
defineEmits(['update:modelValue'])
</script>
<template>
<input
:value="modelValue"
@input="$emit('update:modelValue', $event.target.value)"
>
</template>Or using v-model with a custom name:
<CustomInput v-model:search="term">
Which would use search prop and update:search event.
Modifiers for v-model
Vue provides a few built-in modifiers to tweak v-model behavior:
.lazy– listens tochangeinstead ofinput(updates on blur).number– automatically converts input string to a number.trim– trims whitespace from user input
Example:
<input v-model.number="age" /> <!-- ensures age is a number -->
Basically, v-model removes the boilerplate of manually syncing form inputs with data. It’s smart, flexible, and works seamlessly across native inputs and custom components. Just remember it’s not magic — it’s just a clean abstraction over events and props.
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