Typescript: Property ‘foo’ does not exist on type ‘Vue’

Today I was plagued with an annoying bug! I was banging my head for a while!

Let’s get into it! For example purposes, I will show you a snippet of how my code looked like:

export default Vue.extend({
    name: 'justaname',
    data() {
        return {
            currentSlide: 0 as number
        };
    },
    computed: {
        internalOpen: {
            get(): boolean {
                return this.value;
            },
            set(val) {
                (this as any).$emit('input', false);
            },
        },
    },
});

This resulted in the following error:

Typescript: Property ‘currentSlide’ does not exist on type ‘Vue’

When I added a type on my setter val the error was no longer present!

set(val: boolean) {
  (this as any).$emit('input', false);
},

Basically if your setter is missing a type you’ll get this strange error.

Hopefully this helps some people out there! 😄