> For AI agents: the complete documentation index is available at https://rslint.rs/llms.txt, the full documentation bundle is available at https://rslint.rs/llms-full.txt.

# no-dupe-else-if

[Added in v0.5.0](https://github.com/web-infra-dev/rslint/releases/tag/v0.5.0)
## Configuration

| Preset                   | Configured Value |
| ------------------------ | ---------------- |
| ✅ js.configs.recommended | `"error"`        |


```ts title=rslint.config.ts
import { defineConfig, js } from '@rslint/core';

export default defineConfig([
  js.configs.recommended,
  {
    rules: {
      'no-dupe-else-if': 'error',
    },
  },
]);
```

## Rule Details

Disallow duplicate conditions in if-else-if chains. If an `else if` condition is identical to a previous condition in the same chain, the branch can never execute.

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

```javascript
if (a) {
  foo();
} else if (a) {
  bar();
}

if (a) {
  foo();
} else if (b) {
  bar();
} else if (a) {
  baz();
}
```

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

```javascript
if (a) {
  foo();
} else if (b) {
  bar();
}

if (a === 1) {
  foo();
} else if (a === 2) {
  bar();
}

if (a) {
  foo();
} else if (b) {
  bar();
} else {
  baz();
}
```

## Original Documentation

- [ESLint: no-dupe-else-if](https://eslint.org/docs/latest/rules/no-dupe-else-if)
- [Source code](https://github.com/eslint/eslint/blob/v10.8.1/lib/rules/no-dupe-else-if.js)