Vuetify Form Validation - defining ES6 rules for matching inputs

Rules are not the proper way of handling field confirmation. emailConfirmationRules are triggered only when emailConfirmation changes, but if you change email again, your fields won't match anymore without any break of rules.

You have to handle this manually:

methods: {
  emailMatchError () { 
    return (this.email === this.emailConfirmation) ? '' : 'Email must match'
  }
}

<v-text-field v-model='emailConfirmation' :error-messages='emailMatchError()'></v-text-field>

There may be an alternative way of doing this with vee-validate too.

You can accomplish the same with a computed rule.

computed: {
    emailConfirmationRules() {
      return [
        () => (this.email === this.emailToMatch) || 'E-mail must match',
        v => !!v || 'Confirmation E-mail is required'
      ];
    },
}