---
title: capitalize
tags: string,intermediate
firstSeen: 2017-12-17T16:41:31+02:00
lastUpdated: 2020-11-01T20:50:57+02:00
---

Capitalizes the first letter of a string.

- Use array destructuring and `String.prototype.toUpperCase()` to capitalize the first letter of the string.
- Use `Array.prototype.join('')` to combine the capitalized `first` with the `...rest` of the characters.
- Omit the `lowerRest` argument to keep the rest of the string intact, or set it to `true` to convert to lowercase.

```js
const capitalize = ([first, ...rest], lowerRest = false) =>
  first.toUpperCase() +
  (lowerRest ? rest.join('').toLowerCase() : rest.join(''));
```

```js
capitalize('fooBar'); // 'FooBar'
capitalize('fooBar', true); // 'Foobar'
```