# ember/no-side-effects

💼 This rule is enabled in the ✅ `recommended` [config](https://github.com/ember-cli/eslint-plugin-ember#-configurations).

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When using computed properties, do not introduce side effects. Side effects make it much more difficult to reason about the origin of changes.

This rule currently disallows the following side-effect-causing statements inside computed properties:

- `this.set('x', 123);`
- `this.setProperties({ x: 123 });`
- `this.x = 123;`

Note that other side effects like network requests should be avoided as well.

## Examples

```js
import Component from '@ember/component';
import { alias, filterBy } from '@ember/object/computed';

export default Component.extend({
  init(...args) {
    this.users = [
      { name: 'Foo', age: 15 },
      { name: 'Bar', age: 16 },
      { name: 'Baz', age: 15 },
    ];
    this._super(...args);
  },

  // GOOD:
  fifteenGood: filterBy('users', 'age', 15),
  fifteenAmountGood: alias('fifteen.length'),

  // BAD:
  fifteenAmountBad: 0,
  fifteenBad: computed('users', function () {
    const fifteen = this.users.filterBy('items', 'age', 15);
    this.set('fifteenAmountBad', fifteen.length); // SIDE EFFECT!
    return fifteen;
  }),
});
```

## Configuration

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| Name                | Description                                                                                    | Type    | Default |
| :------------------ | :--------------------------------------------------------------------------------------------- | :------ | :------ |
| `catchEvents`       | Whether the rule should catch function calls that send actions or events.                      | Boolean | `true`  |
| `checkPlainGetters` | Whether the rule should check plain (non-computed) getters in native classes for side effects. | Boolean | `true`  |

<!-- end auto-generated rule options list -->