WIP Event delegation for #956

[sagalbot]

• adds a mapKeydown {Function} prop: receives an object and expects a returned object
• adds selectOnKeyCodes {Array} prop: array of keycodes to trigger a typeahead select
• allows for hooking into keydown events that are bound to the search input

mapKeydown is a high level function that maps keycodes to event handlers for the search input. It can be used to alter any default behavior.

selectOnKeyCodes is more of a shortcut prop, allowing you to choose what keyCodes should trigger a selection.

There's overlap between the two, but one is much more powerful than the other.

tag on space and comma with mapKeydown

<template>
  <v-select
    taggable
    multiple
    no-drop
    :map-keydown="handlers"
    placeholder="try tagging with space or comma to submit"
  />
</template>

<script>
export default {
  methods: {
    handlers (map, vm) {
      const createTag = e => {
        e.preventDefault();
        vm.typeAheadSelect();
        vm.searchEl.focus();
      };

      return {
        ...map, //  defaults
        32: createTag,  //  space
        188: createTag,  //  comma
      };
    },
  },
};
</script>

tag on space and comma with selectOnKeyCodes

<!-- select on tab, space, return, or comma -->
<v-select :selectOnKeyCodes="[9, 32, 13, 188]" /> 

---

Todo

• integrate Prevent enter event while composing #900 into event handling

---

Closes #956
Closes #377
Closes #502
Closes #847
Closes #900
Closes #849

[coveralls]

Coverage increased (+0.2%) to 95.982% when pulling 1e6b0e9 on fix-956-event-delegation into ceb42b4 on master.

[Meekohi]

👍