how to capitalize first letter of word in javascript 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: capitalize first carater js

const capitalize = (s) => {
  if (typeof s !== 'string') return ''
  return s.charAt(0).toUpperCase() + s.slice(1)
}

capitalize('flavio') //'Flavio'
capitalize('f')      //'F'
capitalize(0)        //''
capitalize({})       //''