Change data values in instance variable when component loading in vue

I use Vue router for loading components in Laravel.I want to change 'show' value in instance variable when I click router-link.How can I do do this?

<router-link to="/login">Login</router-link>

Instance Variable:

const app = new Vue({
    el: '#app',
    data: function() {
        return {
            show: true
        }
    },
    router
});

Login Component :

<template>
  <div>Login component</div>
</template>

via Chebli Mohamed