upperFirst (Lodash Compatibility)

::: warning Use upperFirst from es-toolkit

This upperFirst function operates slowly due to conversion logic for handling null or undefined.

Use the faster and more modern upperFirst from es-toolkit instead.

:::

Converts the first character of a string to uppercase.

const upperCased = upperFirst(str);

Usage

upperFirst(str)

Use upperFirst when you want to capitalize only the first character of a string. The remaining characters stay unchanged.

import { upperFirst } from 'es-toolkit/compat';

// String starting with lowercase
upperFirst('fred');
// Returns: 'Fred'

// String already starting with uppercase
upperFirst('Fred');
// Returns: 'Fred'

// All uppercase string
upperFirst('FRED');
// Returns: 'FRED'

null or undefined is treated as an empty string.

import { upperFirst } from 'es-toolkit/compat';

upperFirst(null); // ''
upperFirst(undefined); // ''

Parameters

• str (string, optional): The string to convert the first character to uppercase.

Returns

(string): Returns the string with the first character converted to uppercase.