# oxc/no-optional-chaining

> Disallow optional chaining (`?.`)

Engines older than ES2020 can't parse `?.`, so a file that uses it fails to load there. If a compiler lowers it for a target like that, each `?.` turns into temporary variables and `null` and `undefined` checks, which makes the output larger.

The rule reports each chain once, no matter how many `?.` it has.

{/* 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]
"oxc/no-optional-chaining" = "error" # or "warn"
```

Every option, set to its default:

```toml bunfig.toml
[lint.rules]
"oxc/no-optional-chaining" = ["error", {
  message = "", # string
}]
```

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

## Examples

Reported:

{/* bad {"count": 1} */}
```js
const city = user?.address?.city;
```

{/* bad {"count": 2} */}
```js
const first = items?.[0];
onSave?.(first);
```

Not reported:

{/* good */}
```js
const city = user && user.address && user.address.city;

if (onSave) {
  onSave(city);
}
```

## Options

| Option | Default | What it does |
| --- | --- | --- |
| `message` | `""` | Text to show as help under the report, for example why your project doesn't allow `?.`. |

{/* bad {"options": [{"message": "We ship ES2016 without a compile step."}]} */}
```js
const city = user?.address;
```

## When not to use it

Every current browser and runtime supports `?.`. Only use this rule if your code has to run on older ones.