JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://rawgit.com/yyx990803/vue/dev/dist/vue.js"></script>
<input type="text" v-model="bar | foo" /> {{bar}}

Vue

new Vue({
    el: 'body',
    data: {
        bar: 'asd'
    },
    filters: {
        foo: {
            read: function(val) {
                return val.toUpperCase()
            },
            write: function(val, oldval) {
                return val.toLowerCase()
            }
        }
    }
})