# promise/prefer-await-to-then

> Require `await` instead of `then()`, `catch()` and `finally()`

A chain of `then()` callbacks puts each step in its own function, so steps can't share variables, and loops, early returns and `try`/`catch` don't work across them. With `await`, the same code is ordinary statements.

Not reported:

- the call that a `return` statement returns, as in `return load().then(parse)`
- a chain inside an `await` or `yield` expression, unless you set `strict`
- a `then`, `catch` or `finally` method on something that clearly isn't a promise, such as an object literal or `new Parser()`

{/* 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]
"promise/prefer-await-to-then" = "error" # or "warn"
```

Every option, set to its default:

```toml bunfig.toml
[lint.rules]
"promise/prefer-await-to-then" = ["error", {
  strict = false,
}]
```

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

## Examples

Reported:

{/* bad {"count": 2} */}
```js
function showUser(id) {
  fetchUser(id)
    .then(user => render(user))
    .catch(err => showError(err));
}
```

Not reported:

{/* good */}
```js
async function showUser(id) {
  try {
    render(await fetchUser(id));
  } catch (err) {
    showError(err);
  }
}

function loadConfig(path) {
  return readFile(path, "utf8").then(JSON.parse);
}

const parser = new Parser();
parser.then(render);
```

In a longer chain, `return` only exempts the last call. Here the `then()` is reported:

{/* bad {"count": 1} */}
```js
function loadConfig(path) {
  return readFile(path, "utf8").then(JSON.parse).catch(useDefaults);
}
```

## Options

| Option | Default | What it does |
| --- | --- | --- |
| `strict` | `false` | Also report `then()`, `catch()` and `finally()` inside an `await` or `yield` expression. |

{/* good */}
```js
async function findUser(id) {
  const user = await fetchUser(id).catch(() => null);
  return user ?? guest;
}
```

{/* bad {"options": [{"strict": true}]} */}
```js
async function findUser(id) {
  const user = await fetchUser(id).catch(() => null);
  return user ?? guest;
}
```