ucwords in JavaScript - Equivalent to PHP's ucwords() Returns a string with the first letter in upper case of each word.

ucwords.js

String.prototype.ucwords = function() {
  str = this.toLowerCase();
  return str.replace(/(^([a-zA-Z\p{M}]))|([ -][a-zA-Z\p{M}])/g,
  	function(s){
  	  return s.toUpperCase();
	});
};

Para mayuscula en cada palabra:

var lsCadena = "hola MUNDO";

lsCadena = lsCadena.toLowerCase().replace(/\b[a-z]/g, function(letra) {
    return letra.toUpperCase();
});

//salida: Hola Mundo

Para mayuscula en la primera letra:

var lsCadena = "hola MUNDO";

lsCadena = lsCadena .toLowerCase();
lsCadena = lsCadena .charAt(0).toUpperCase() + lsCadena .slice(1);

//salida: Hola mundo

@EdwinBetanc0urt

Como respuesta a esto tambien si quieres ahorrarte el paso de declarar lsCadena a lowerCase lo puedes hacer en el mismo lsCadena.slice(1).toLowerCase();

Pero tu forma sirve!

I use str.toLowerCase().replace(/(?<= )[^\s]|^./g, a=>a.toUpperCase())

I use str.toLowerCase().replace(/(?<= )[^\s]|^./g, a=>a.toUpperCase())

Thanks, this worked.

I use str.toLowerCase().replace(/(?<= )[^\s]|^./g, a=>a.toUpperCase())

Thanks, this worked.

Careful though, that last one doesn't work in Safari. For some reason, it doesn't support lookbehind regex.
So I am now using (' '+str).replace(/ [\w]/g, a => a.toLocaleUpperCase()).trim(); ...