Convert string to camelCase.

toCamelCase.php

<?php
/**
 * Convert string to camelCased format.
 *
 * supports strings with "-" dash case
 *
 * @param string $str
 * @param boolean $capitalise_first_char
 *
 * @return string $str camelCased string.
 */
function to_camel_case( $str, $capitalise_first_char = false ) {
	// Removes '-' or '_' from start/end of the string.
	$str = trim( $str, '-_' );

	if ( $capitalise_first_char ) {
		$str[0] = strtoupper( $str[0] );
	}
	// Match first letter of the string after "-" or "_" and change it to uppercase,
	return preg_replace_callback(
		'/[_-]([a-z])/', function( $match ) {
			return strtoupper( $match[1] );
		}, $str
	);
}