Assign a value in Vue.js onchange of input - vue.js

Question

I there guy's im struggling with a form that i need to complete using Vue.JS. Basically i need that the value of the field 'price_vat' its updated with some calculations evry time that input called 'price_user' is updated. Usign jquery evrything is going as well. Butt data is not passed to POST method using Vue.
<div class="col-md-6" v-show="form.active">
<div class="form-group">
<label >{{__('Price')}}</label>
<input type="number" v-model="form.price_user" class="form-control">
</div>
</div>
<div class="col-md-6" v-show="form.active">
<div class="form-group">
<label >{{__('Price with VAT')}}</label>
<input type="number" v-model="form.price_vat" class="form-control">
</div>
</div>

Answer 1

if i understand you correctly,, you want form.price_vat to change, every time you change form.price_user by typing inside the input.
you can do this using watch. just add the below your methods in vue:
watch:{
'form.price_user':function():{
this.form.price_vat += 1
},
}
so in this code, you update the value of form.price_vat by 1 every time the form.price_user changes. you can do anything inside the function of watch.
the complete vue part will be :
data(){
return:{
form:{
price_vat :'',
price_user : '',
}
}
},
methods:{},
watch:{
'form.price_user':function():{
this.form.price_vat += 1
},
}