JS.VUE.NO.ARROW.FUNCTIONS.IN.WATCH

Disallow using arrow functions to define watcher

Rule Details

This rules disallows using arrow functions to defined watcher.The reason is arrow functions bind the parent context, so this will not be the Vue instance as you expect.(see here for more details (https://vuejs.org/api/options-state.html#watch))

{'vue/no-arrow-functions-in-watch': ['error']}

Copy

<script>
export default {
  watch: {
    /* GOOD */
    a: function (val, oldVal) {
      console.log('new: %s, old: %s', val, oldVal)
    },
    b: 'someMethod',
    c: {
      handler: function (val, oldVal) { /* ... */ },
      deep: true
    },
    d: {
      handler: 'someMethod',
      immediate: true
    },
    e: [
      'handle1',
      function handle2 (val, oldVal) { /* ... */ },
      {
        handler: function handle3 (val, oldVal) { /* ... */ },
        /* ... */
      }
    ],
    'e.f': function (val, oldVal) { /* ... */ },

    /* BAD */
    foo: (val, oldVal) => {
      console.log('new: %s, old: %s', val, oldVal)
    }
  }
}
</script>

Options

Nothing.