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# no-func-assign

[Added in v0.4.0](https://github.com/web-infra-dev/rslint/releases/tag/v0.4.0)
## 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-func-assign': 'error',
    },
  },
]);
```

## Rule Details

Disallows reassigning variables that were declared as function declarations. Reassigning a function declaration is almost always a mistake, as it overwrites the function with a different value. This rule checks for assignments, increment/decrement operations, and destructuring assignments that target a function name.

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

```javascript
function foo() {}
foo = bar;

function foo() {}
foo += 1;

function foo() {}
[foo] = arr;
```

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

```javascript
function foo() {}
foo();

var foo = function () {};
foo = bar; // foo is a variable, not a function declaration

function foo(foo) {
  foo = bar; // foo is a parameter, not the function
}

function foo() {
  var foo = bar; // foo is a local variable, not the function
}
```

## Original Documentation

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