locutus/esm/ruby/String/capitalize.js

Locutus other languages' standard libraries to JavaScript for fun and educational purposes

export function capitalize(str) {
    // parity verified: Ruby 3.3
    //      discuss at: https://locutus.io/ruby/String/capitalize/
    //     original by: Kevin van Zonneveld (https://kvz.io)
    //          note 1: Returns a copy of str with the first character converted to uppercase
    //          note 1: and the remainder to lowercase.
    //       example 1: capitalize('hello')
    //       returns 1: 'Hello'
    //       example 2: capitalize('HELLO')
    //       returns 2: 'Hello'
    //       example 3: capitalize('123ABC')
    //       returns 3: '123abc'
    str = str + '';
    if (str.length === 0) {
        return str;
    }
    return str.charAt(0).toUpperCase() + str.slice(1).toLowerCase();
}