# `res.json()`

Sends a JSON response composed of the specified `data`.

### Usage
```usage
return res.json(data);
```

### Details

When an object or array is passed to it, this method is identical to `res.send()`. Unlike `res.send()`, however, `res.json()` may also be used for explicit JSON conversion of non-objects (null, undefined, etc.), even though these are technically not valid JSON.

### Examples

```javascript
return res.json({ firstName: 'Tobi' });
```

```javascript
return res.status(201).json({ id: 201721 });
```

```javascript
var leena = await User.findOne({ firstName: 'Leena' });
if (!leena) { return res.notFound(); }
return res.json(leena.id);//« you can send down primitives, like numbers
```

### Notes
> + Don't forget that this method's name is all lowercase.
> + This method is **terminal**, meaning that it is generally the last line of code your app should run for a given request (hence the advisory usage of `return` throughout these docs).




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