# explicit-timer-delay

📝 Enforce or disallow explicit `delay` argument for `setTimeout()` and `setInterval()`.

💼 This rule is enabled in the following [configs](https://github.com/sindresorhus/eslint-plugin-unicorn#recommended-config): ✅ `recommended`, ☑️ `unopinionated`.

🔧 This rule is automatically fixable by the [`--fix` CLI option](https://eslint.org/docs/latest/user-guide/command-line-interface#--fix).

<!-- end auto-generated rule header -->
<!-- Do not manually modify this header. Run: `npm run fix:eslint-docs` -->

When using [`setTimeout()`](https://developer.mozilla.org/en-US/docs/Web/API/setTimeout) or [`setInterval()`](https://developer.mozilla.org/en-US/docs/Web/API/setInterval), the `delay` parameter is optional and defaults to `0`. This rule allows you to enforce whether the `delay` argument should always be explicitly provided or omitted when it's `0`.

## Examples

```js
// ❌
setTimeout(() => console.log('Hello'));

// ✅
setTimeout(() => console.log('Hello'), 0);
```

```js
// ❌
setInterval(callback);

// ✅
setInterval(callback, 0);
```

```js
// ❌
window.setTimeout(() => console.log('Hello'));

// ✅
window.setTimeout(() => console.log('Hello'), 0);
```

```js
// ❌
globalThis.setInterval(callback);

// ✅
globalThis.setInterval(callback, 0);
```

```js
// ✅
setTimeout(() => console.log('Hello'), 1000);
setInterval(callback, 100);
```

## Options

Type: `string`\
Default: `'always'`

- `'always'` (default)
  - Require explicit `delay` argument for clarity.
- `'never'`
  - Disallow explicit `0` delay, prefer implicit default. Non-zero delays are still allowed.

### `'never'`

```js
{
	'unicorn/explicit-timer-delay': ['error', 'never']
}
```

```js
// ❌
setTimeout(() => console.log('Hello'), 0);

// ✅
setTimeout(() => console.log('Hello'));
```

```js
// ❌
setInterval(callback, 0);

// ✅
setInterval(callback);
```

```js
// ❌
window.setTimeout(() => console.log('Hello'), 0);

// ✅
window.setTimeout(() => console.log('Hello'));
```

```js
// ❌
globalThis.setInterval(callback, 0);

// ✅
globalThis.setInterval(callback);
```

```js
// ✅
setTimeout(() => console.log('Hello'), 1000);
globalThis.setInterval(callback, 100);
```