to capital leter js code example

Example 1: uppercase javascript

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

Example 2: javascript first letter uppercase

const upperCase = function(names){
    const toLower = names.toLowerCase().split(' ');
    const namesUpper = [];
    for(const wordName of toLower){
        namesUpper.push(wordName[0].toUpperCase() + wordName.slice(1));
    }
    return namesUpper.join(' ');
}