# no-declarations-before-early-exit

📝 Disallow declarations before conditional early exits when they are only used after the exit.

💼 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` -->

Declare variables as close as possible to where they are used. If a variable is declared before a guard clause but only used after it, the declaration can be moved below the guard. This avoids unnecessary initialization on the early-exit path and keeps the variable scope tighter.

This rule reports declarations before `return`, `throw`, `break`, and `continue` guard clauses.

## Examples

```js
// ❌
function foo(bar) {
	const result = 1;
	if (!bar) {
		return;
	}

	console.log(result);
}
```

```js
// ✅
function foo(bar) {
	if (!bar) {
		return;
	}

	const result = 1;
	console.log(result);
}
```

```js
// ❌
function foo(bar) {
	const result = 1;
	if (!bar) {
		throw new Error();
	}

	console.log(result);
}
```

```js
// ✅
function foo(bar) {
	if (!bar) {
		throw new Error();
	}

	const result = 1;
	console.log(result);
}
```

```js
// ❌
function foo(bar) {
	const result = getResult();
	if (!bar) {
		return;
	}

	console.log(result);
}
```

The last example is reported without an autofix because moving a function call can change observable behavior.

## Limitations

This rule intentionally uses a simple statement-list scan instead of full data-flow analysis. It only checks declarations and guard clauses that are direct children of the same block or top-level program. Switch cases are only checked when the case body is wrapped in a block. Non-adjacent declarations with nontrivial initializers are ignored because moving them across intervening statements can change values or timing. Declarations are also ignored when the initializer and the guard share a variable that either side mutates, since reordering them would change behavior (for example, `const x = array.pop()` before `if (array.length > 0)`).

Declarations whose initializer contains `await` or `yield` are ignored: moving them below the guard would evaluate the guard condition before the suspension instead of after it, which can change observable timing.

Declarations initialized by a React hook call (for example, `const value = useMemo(…)`) are ignored, because hooks must run unconditionally and moving one below an early exit would violate the [Rules of Hooks](https://react.dev/reference/rules/rules-of-hooks).