---
url: /docs/guide/usage/linter/rules/unicorn/explicit-timer-delay.md
---

### What it does

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

### Why is this bad?

When using `setTimeout()` or `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

Examples of **incorrect** code for this rule:

```javascript
setTimeout(() => console.log("Hello"));
setInterval(callback);
window.setTimeout(() => console.log("Hello"));
globalThis.setInterval(callback);
```

Examples of **correct** code for this rule:

```javascript
setTimeout(() => console.log("Hello"), 0);
setInterval(callback, 0);
window.setTimeout(() => console.log("Hello"), 0);
globalThis.setInterval(callback, 0);
setTimeout(() => console.log("Hello"), 1000);
setInterval(callback, 100);
```

With the `"never"` option, explicit `0` delays are disallowed and
non-zero delays are still allowed.

Examples of **incorrect** code for the `"never"` option:

```javascript
setTimeout(() => console.log("Hello"), 0);
setInterval(callback, 0);
window.setTimeout(() => console.log("Hello"), 0);
globalThis.setInterval(callback, 0);
```

Examples of **correct** code for the `"never"` option:

```javascript
setTimeout(() => console.log("Hello"));
setInterval(callback);
window.setTimeout(() => console.log("Hello"));
globalThis.setInterval(callback);
setTimeout(() => console.log("Hello"), 1000);
globalThis.setInterval(callback, 100);
```

## Configuration

This rule accepts one of the following string values:

### `"always"`

Require explicit `delay` argument for clarity.

### `"never"`

Disallow explicit `0` delay, prefer implicit default.

## How to use

## Version

This rule was added in v1.73.0.

## References