Solucio classe text

function text(){

var text= "cadena de caracters";

this.afegirCaracter=function(caracter)  //mètode agefirCaracter
{
	return text+=""+caracter;
}


this.contarVocals=function()   //mètode contarVocals
{
var cont=0;
var texto=text.split("");
for (var i = texto.length - 1; i >= 0; i--) {
	if(texto[i]=='a' ||texto[i]=='e'|| texto[i]=='i' ||texto[i]=='o' ||texto[i]=='u'){
		cont++;
	}
};

return cont;
}


this.mostrarText=function()   //mètode mostrarText
{
	console.log(text);
}

}//tanquem la classe




var texto= new text();
texto.afegirCaracter("a");
texto.contarVocals();
texto.mostrarText();

AMB PROTOTYPE

function Text(num) {
    this.num=num;
}

Text.prototype.cadena=[this.num];    //creamos el array cadena
   


Text.prototype.afegirCadena=function(nombre){
  var nom=nombre.split("");
  
  
  for(i=0;i<this.num;i++){
       this.cadena[i]=nom[i];
   }
  this.cadena.join("");
 console.log(this.cadena);

}

Text.prototype.contarVocal=function(){
    var cont=0;
   for(i=0;i<this.num;i++){
       if(this.cadena[i]== 'a' || this.cadena[i]== 'e' || this.cadena[i]== 'i' || this.cadena[i]== 'o'|| this.cadena[i]== 'u'){
           cont++;
       }
   }
    
    console.log(cont);
}

Text.prototype.mostrar=function(){
    var texto="";
    for(i=0;i<this.num;i++){
        texto+=this.cadena[i];
    }
    console.log(texto);
}
var texto=new Text(10);
texto.afegirCadena("hola");
texto.contarVocal();