Feature request: v-empty

[asmaps]

As stated in #677 currently you have to wrap a v-for with an if to catch if an array is empty. I'd love a tag like v-empty to do that. It would work like v-else and you put it right after a v-for (maybe also v-else could also be reused for that?).
The v-empty block triggeres if the v-for list is empty. Just like the equivalent django template tag: https://docs.djangoproject.com/en/1.9/ref/templates/builtins/#for-empty

Example:

<div v-for="(index, item) in items">
  {{ index }} {{ item.message }}
</div>
<div v-empty>
  <p>Sorry, no elements yet.</p>
</div>

[phanan]

While I'm a fan of little utilities like this, a client-side JavaScipt library shouldn't cover them due to size and performance issues. Server-side frameworks like Laravel and Django, on the other hand, have all my support.

[taylorzane]

@asmaps You could also simply use v-if or v-show.

<div v-for="(index, item) in items">
  {{ index }} {{ item.message }}
</div>
<div v-if="items.length == 0">
  <p>Sorry, no elements yet.</p>
</div>

If you needed to handle both Arrays and Objects, a basic method implementation could be:

{
  isEmpty (value) {
    if (!!value && value instanceof Array) {
      return value.length < 1
    }

    if (!!value && typeof value === 'object') {
      for (var key in value) {
        if (hasOwnProperty.call(value, key)) {
          return false
        }
      }
    }

    return !value // Fallback for strings, etc.
  }
}

[asmaps]

@taylorzane sure I can use v-if. For v-else it's the same, I could also use v-if="!ifCondition" instead of v-else, but it's a convenience feature and prevents code duplication.
With @phanan s reason you could also argue against v-else. But yes, somewhere a line has to be drawn. If it's here that's okay for me, just wanted to ask because I'm used to it from django and find it very useful.

[phanan]

With @phanan s reason you could also argue against v-else.

Exactly. And that's why we had internal discussions about v-else as well ;)

[rpkilby]

performance issues

@phanan - do you mean the overall size of the library or do you mean rendering performance? This doesn't seem like it would be any more intensive than a v-if/v-else or v-if/v-for.

Also, maybe this could be implemented as a plugin?

[phanan]

do you mean the overall size of the library or do you mean rendering performance?

I meant both, regarding those small utilities.