how to uppercase first letter str in js code example

Example 1: javascript capitalize words

//capitalize only the first letter of the string. 
function capitalizeFirstLetter(string) {
    return string.charAt(0).toUpperCase() + string.slice(1);
}
//capitalize all words of a string. 
function capitalizeWords(string) {
    return string.replace(/(?:^|\s)\S/g, function(a) { return a.toUpperCase(); });
};

Example 2: javascript string first letter lowercase

// for lowercase on first letter
let s = "This is my string"
let lowerCaseFirst = s.charAt(0).toLowerCase() + s.slice(1)