how to capitalize all letters in javascript code example

Example 1: uppercase javascript

var str = "Hello World!";
var res = str.toUpperCase();  //HELLO WORLD!

Example 2: capitalize in javascript

const name = 'flavio'
const nameCapitalized = name.charAt(0).toUpperCase() + name.slice(1)

Example 3: javascript capitalize words

//Updated 
//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(); });
};