Add enum sugar for prop validators

What problem does this feature solve?

For enum props, it’s common to validate the given value against valid enum values like this:

props: {
  position: {
    type: String,
    validator (val) {
      return ['top', 'right', 'bottom', 'left'].includes(val)
    }
  }
}

What does the proposed API look like?

I think it’ll be handy to provide extra convenience by supporting this:

props: {
  position: {
    type: String,
    validator: ['top', 'right', 'bottom', 'left']
  }
}

[sirlancelot]

if you want a shorthand, just use an arrow function:

props: {
  position: {
    type: String,
    validator: (val) => ['top', 'right', 'bottom', 'left'].includes(val)
  }
}

Less magic. It’s Just JavaScript.

[owenallenaz]

If the goal is enum, maybe we should be explicit about it?

props: {
  position: {
    type: String,
    enum: ['top', 'right', 'bottom', 'left']
  }
}

It would only checks exact matches against the passed array. In example from graphQL https://graphql.org/learn/schema/#enumeration-types . From the docs it states two of the benefits.

• Validate that any arguments of this type are one of the allowed values
• Communicate through the type system that a field will always be one of a finite set of values

I think in this case, both apply to Vue, no?