Function

none (dependentKey) ComputedProperty public

Module:	@ember/object

Defined in packages/@ember/object/lib/computed/computed_macros.js:196

import { none } from '@ember/object/computed';

dependentKey

String

returns

ComputedProperty

computed property which returns true if original value for property is null or undefined.

A computed property that returns true if the value of the dependent property is null or undefined. This avoids errors from JSLint complaining about use of ==, which can be technically confusing.

import { set } from '@ember/object';
import { none } from '@ember/object/computed';

class Hamster {
  @none('food') isHungry;
}

let hamster = new Hamster();

hamster.isHungry; // true

set(hamster, 'food', 'Banana');
hamster.isHungry; // false

set(hamster, 'food', null);
hamster.isHungry; // true

Classic Class Example:

import EmberObject, { set } from '@ember/object';
import { none } from '@ember/object/computed';

let Hamster = EmberObject.extend({
  isHungry: none('food')
});

let hamster = Hamster.create();

hamster.isHungry; // true

set(hamster, 'food', 'Banana');
hamster.isHungry; // false

set(hamster, 'food', null);
hamster.isHungry; // true