Vue mixins in Laravel Inertia

I'm trying to create a global helper function via Vue mixin on a Laravel Inertia project to no avail:

//app.js
Vue.mixin({
    methods: {
        myFunction() {
            return 'Returnign from myFunction';
        },
    },
});

new Vue({
...
}).$mount(app);

.

//MyComponent.vue
console.log(myFunction()); // ReferenceError: myFunction is not defined

On a standalone Vue.JS project, this works. Maybe there's something behind the scene in Inertia that prevents the mixin from loading. Can somebody help me understand why this is happening?

Thank you.

You need to add the function in the mixin of the createInertiaApp method in your app.js file.

For instance:

createInertiaApp({
  resolve: (name) => require(`./Pages/${name}.vue`),
  setup ({ el, app, props, plugin }) {
    return createApp({ render: () => h(app, props) })
      .use(plugin)
      .mixin({
        methods: {
          myFunction: () => {
            return 'Returning from myFunction';
          }
        }
      })
      .mount(el)
  }
})