Question

I have this code:

var cadena = prompt("Cadena:");

document.write(mayusminus(cadena));

function mayusminus(cad){
    var resultado = "Desconocido";

    if(cad.match(new RegExp("[A-Z]"))){
        resultado="mayúsculas";
    }else{
        if(cad.match(new RegExp("[a-z]"))){
            resultado="minúsculas";
        }else{
            if(cad.match(new RegExp("[a-zA-z]"))){
            resultado = "minúsculas y MAYUSCULAS";
            }
        }
    }
    return resultado;
}

I always have mayusculas or minusculas, never minusculas y MAYUSCULAS (MIXED), I am learning regexp and dont know my error yet :S

Answer 1

new RegExp("[A-Z]")

matches when any character in cadena is an upper-case letter.
To match when all characters are upper-case, use

new RegExp("^[A-Z]+$")

The ^ forces it to start at the start, the $ forces it to end at the end and the + ensures that between the end there are one or more of [A-Z].