Vue v-on
The v-on directive in Vue instructs the browser, much like event handling in standard JavaScript:
- which event—such as “click,” “keydown,” “mouseover,” etc.—to pay attention to
- How to handle that situation if it arises
Examples using v-on
To show how v-on may be used with various events and different code to run when these events occur, let’s look at a few samples.
Let’s look at a few examples to demonstrate how v-on may be used with different events and different code to run when these events occur.
onclick Event
We can take action in response to predefined events with the v-on directive.
To take action when the element is clicked, use v-on:click.
Example
The <button> element uses the v-on directive to listen for the ‘click’ event. The yellow <div> behind the lightbulb is either visible or hidden depending on whether the ‘click’ event causes the ‘lightOn’ data property to be toggled between ‘true’ and ‘false’.
<div id="app">
<div id="lightDiv">
<div v-show="lightOn"></div>
<img decoding="async" src="data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%200%200'%3E%3C/svg%3E" alt="Vue V-On -" title="Vue V-On 1" data-lazy-src="img_lightBulb.svg"><noscript><img decoding="async" src="img_lightBulb.svg" alt="Vue V-On -" title="Vue V-On 1"></noscript>
</div>
<button v-on:click="lightOn = !lightOn">Switch light</button>
</div>
<script data-minify="1" src="https://codingask.com/wp-content/cache/min/1/vue@3/dist/vue.global.js?ver=1730183021" defer></script>
<script>
const app = Vue.createApp({
data() {
return {
lightOn: false
}
}
})
app.mount('#app')
</script>
oninput Event
To take action when an element receives input—such as a keystroke inside a text field—use v-on:input.
Example
Determine how many keystrokes were made in an input text field:
<div id="app">
<input v-on:input="inpCount++">
<p>{{ 'Input events occured: ' + inpCount }}</p>
</div>
<script data-minify="1" src="https://codingask.com/wp-content/cache/min/1/vue@3/dist/vue.global.js?ver=1730183021" defer></script>
<script>
const app = Vue.createApp({
data() {
return {
inpCount: 0
}
}
})
app.mount('#app')
</script>
mousemove Event
To take action when the mouse pointer passes over an element, use v-on:mousemove.
Example
Whenever the mouse pointer passes over a <div> element, its background color can be changed:
<div id="app">
<p>Move the mouse pointer over the box below</p>
<div v-on:mousemove="colorVal=Math.floor(Math.random()*360)"
v-bind:style="{backgroundColor:'hsl('+colorVal+',80%,80%)'}">
</div>
</div>
<script data-minify="1" src="https://codingask.com/wp-content/cache/min/1/vue@3/dist/vue.global.js?ver=1730183021" defer></script>
<script>
const app = Vue.createApp({
data() {
return {
colorVal: 50
}
}
})
app.mount('#app')
</script>
Use v-on in a v-for Loop
The v-on directive can also be utilized within a v-for loop.
Every iteration within the v-on value has access to the array’s items.
Example
Show a list based on the food array, and then add a click event to each item such that it can modify the image’s source by using a value from the array item.
<div id="app">
<img v-bind:src="imgUrl">
<ol>
<li v-for="food in manyFoods" v-on:click="imgUrl=food.url">
{{ food.name }}
</li>
</ol>
</div>
<script data-minify="1" src="https://codingask.com/wp-content/cache/min/1/vue@3/dist/vue.global.js?ver=1730183021" defer></script>
<script>
const app = Vue.createApp({
data() {
return {
imgUrl: 'img_salad.svg',
manyFoods: [
{name: 'Burrito', url: 'img_burrito.svg'},
{name: 'Salad', url: 'img_salad.svg'},
{name: 'Cake', url: 'img_cake.svg'},
{name: 'Soup', url: 'img_soup.svg'}
]
}
}
})
app.mount('#app')
</script>
Shorthand for v-on
‘@‘ is the shorthand for ‘v-on‘.
Example
Here, ‘@‘ is used in place of ‘v-on‘:
<button @:click="lightOn = !lightOn">Switch light</button>
A bit later in this course, we will begin using the @ syntax.
