Is first character in string upper case

isFirstLetterUpperCase.js

const assert = require( 'assert' );

/**
 * Checks if first letter in string is upper case or lower case
 *
 * @param {string} str - string to test
 * @returns {boolean} Returns bool of whether or not the string starts with upper case
 *
 * @example
 * // returns true
 * isFirstLetterUpperCase( 'Stuff' );
 *
 */

function isFirstLetterUpperCase ( str ) {
	assert( typeof str === 'string', 'Must supply a string');

	return /^[A-Z]/.test( str );
}

module.exports = isFirstLetterUpperCase;