Fund: Rule proposal: `prefer-smaller-scope` (like `prefer-const`, but across scopes)

Rule proposal: prefer-smaller-scope (like prefer-const, but across scopes)

3 years ago

👍

Context:

This is basically what prefer-const does:

function foo () {
	  let a; // ERROR: Use `const` instead (prefer-const)
	  a = 1;
	  return a;
}

Except that is should work across scopes

Fail

function foo () {
	let a;
	while (Math.random() > 0.5) {
		a = get(); // ERROR: Use `const` instead (prefer-smaller-scope)
		console.log(a);
	}
}

function foo () {
	while (Math.random() > 0.5) {
		const a = get(); // ✅
		console.log(a);
	}
}

function foo () {
	let a;
	while (Math.random() > 0.5) {
		a = get(a); // ✅ `a` is used before assignment 
		console.log(a);
	}
}

function foo () {
	let a;
	while (Math.random() > 0.5) {
		a = get();
	}
	console.log(a); // ✅ `a` is actually used in the outer scope
}