# no-lone-blocks

> Disallow blocks that do nothing

Braces that aren't the body of an `if`, a loop or a function only do something if they contain a `let`, `const` or `class` declaration, or a `function` declaration in strict mode. Those are scoped to the block. Otherwise the braces change nothing. They're often left over after a condition was deleted, so a reader wonders what's missing.

{/* Generated by src/codegen/lint-rule-docs.ts. Do not edit this section. */}

## Configure

Off by default. To turn it on:

```toml bunfig.toml
[lint.rules]
"no-lone-blocks" = "error" # or "warn"
```

{/* End of the generated section. */}

## Examples

Reported:

{/* bad {"count": 2} */}
```js
{
  loadConfig();
}

function start() {
  connect();
  {
    listen();
  }
}
```

Not reported:

{/* good */}
```js
loadConfig();

function start() {
  connect();
  listen();
}
```

Not reported, because `started` only exists inside the braces:

{/* good */}
```js
{
  const started = Date.now();
  loadConfig();
  console.log(Date.now() - started);
}
```

Braces around all the statements in a `case` are fine too:

{/* good */}
```js
switch (event.type) {
  case "open": {
    open(event.id);
    break;
  }
}
```

A block that's the only thing in a function or in another block is reported even if it declares something. The braces around it already limit the scope:

{/* bad */}
```js
function start() {
  {
    const port = 3000;
    listen(port);
  }
}
```