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v-on attribute added in HTML tags to listen to the events.v-on attribute is the name of a method defined in the methods property. The specified method is called when the event is emitted.
<button v-on:eventName='methodName'>Try it</button>
<script>
var vm = new Vue({
//...
methods:{
methodName: function(event){
//code to execute..
}
}
})
</script>
- eventName is the name of the event: click, input, mouseenter, etc.click event:
<div id='demo'>
<h1>{{hi}}</h1>
<button v-on:click='greet'>Try it</button>
</div>
<script>
var vue_ob = new Vue({
el: '#demo',
data: {hi: ''},
methods:{
greet: function(ev){
this.hi ='Hello brother';
}
}
})
</script>
v-on to pass a value, and the event instance to the method:
<button v-on:eventName='methodName("string", $event)'>Try it</button>
<script>
var vm = new Vue({
//...
methods:{
methodName: function(value, event){
//code to execute..
}
}
})
</script>
<div id='demo'>
<h1>{{hi}}</h1>
<a href='/' v-on:click='test("The link not works", $event)'>Open the page</a>
</div>
<script>
var vue_ob = new Vue({
el: '#demo',
data: {hi: ''},
methods:{
test: function(val, ev){
this.hi = val;
if(ev){
ev.preventDefault();
alert('Link address: '+ ev.target.href);
}
}
}
})
</script>
v-on directive, but without an argument.Note: With this method you cannot add modifier, nor pass an argument to the event handler, but it is automatically passed the event instance object.
<div id='demo'>
<div v-bind:style='styleobj' v-on='{mouseenter:bground, mouseleave:bground}'>Place the mouse here</div>
</div>
<script>
var vue_ob = new Vue({
el: '#demo',
data: {
styleobj:{background:'#fbfc00', height:'111px', width:'111px'}
},
methods:{
bground: function(ev){
let bgr ={mouseenter:'#bbbbfe', mouseleave:'#00e000'};
this.styleobj.background = bgr[ev.type];
}
}
})
</script>
v-on attribute. They are directive postfixes denoted by a dot.prevent - calls event.preventDefault().
<form action='/' id='frm1' v-on:submit.prevent='test'>
The submit event will not reload the page, but will call a Vue method.<br>
<input type='text' name='inp1' value='MarPlo'/> <input type='submit' value='Send'/>
<div>{{text}}</div>
</form>
<script>
var vue_ob = new Vue({
el: '#frm1',
data: {
text:''
},
methods:{
test: function(ev){
this.text = ev.target.inp1.value;
}
}
})
</script>
once - trigger handler at most once.
<div id='demo'>
Nr. clicks: <b>{{nrc}}</b><br>
Only one click is emitted: <button v-on:click.once='nrc +=1'>Click</button>
</div>
<script>
var vue_ob = new Vue({
el: '#demo',
data: {
nrc:0
}
})
</script>
self - only trigger handler if event was dispatched from this element, not from a child element.
<div id='demo'>
Click event is registered with '<b>self</b>' modifier on Parent.<br>
If you click on the Child element, it will have no effect.<br>
Nr. clicks: <b>{{nrc}}</b><br>
<div style='background:#b0b0fe; height:144px; text-align:center; width:220px' v-on:click.self='nrc +=1'>
Parent
<div style='background:#00da00; margin:12px; height:88px; width:115px'>Child</div>
</div>
</div>
<script>
var vue_ob = new Vue({
el: '#demo',
data: {
nrc:0
}
})
</script>
left | middle | right - only trigger handler for left, middle or right button mouse events.
<div id='demo'>
It registers the clicks on the right button mouse: <b>v-on:click.right.prevent</b>.<br>
The <b>prevent</b> modifier is added to stop default behavior (here to stop opening menu on right click).<br><br>
Nr. clicks: <b>{{nrc}}</b><br>
<div style='background:#afaffe; height:144px; text-align:center; width:222px' v-on:click.right.prevent='nrc +=1'>
Right click here
</div>
<script>
var vue_ob = new Vue({
el: '#demo',
data: {
nrc:0
}
})
</script>
You can chain multiple modifiers on an event with v-on, see in the example above: v-on:click.right.prevent.
v-on when listening for key events.v-on.onkeydown.ctrl.enter
<div id='demo'>
Add some text, then press enter.
<form action='/' v-on:keydown.enter.prevent='submitFrm'>
<input type='text' value='MarPlo'/>
<div v-html='str'></div>
</form>
</div>
<script>
var vue_ob = new Vue({
el: '#demo',
data: {
str:''
},
methods:{
submitFrm:function(ev){
this.str ='The form submits the text: <b>'+ ev.target.value +'</b>';
}
}
})
</script>
v-on: with the character @ in Vue syntax, as a shorthand for v-on:.v-on:[event]='methodName' //OR @[event]='methodName'
<div id='demo'>
<h1>{{hi}}</h1>
<button @[ev_name]='greet'>Try it</button>
</div>
<script>
var vue_ob = new Vue({
el: '#demo',
data: {
hi: '',
ev_name: 'click'
},
methods:{
greet: function(ev){
this.hi ='Forgive the past, love the present, trust the future.';
}
}
})
</script>
<meta name="description" content="70-160 characters that describes the content of the page" />
#some_id {
clear: both;
}var divs = document.getElementsByTagName("div");
var nr_divs = divs.length;
alert(nr_divs);$arr =[7, 8, "abc", 10); $nri = count($arr); echo $nri; // 4