Function app.directive()

Registers a global custom directive if passing
both a name string and a directive definition, or
retrieves an already registered one if only the
name is passed.

interface App {
  directive(name: string): Directive | undefined
  directive(name: string, directive: Directive): this
}

import { createApp } from 'vue'

const app = createApp({
  /* ... */
})

// register (object directive)
app.directive('my-directive', {
  /* custom directive hooks */
})

// register (function directive shorthand)
app.directive('my-directive', () => {
  /* ... */
})

// retrieve a registered directive
const myDirective = app.directive('my-directive')