Question

The function I was trying to use wasn’t working, so I tested the length selection (should be one):

$('header').append('<p id="ancho_ventana"></p>');
$(document).ready(function(){
    alert(('p#ancho_ventana').length); //outputs "15"
});

Also tried with

var ancho = $('<p id="ancho_ventana"></p>').hide();
$(document).ready(function(){
    $(window).bind('resize',function(){
       alert(('p#ancho_ventana').length);   
    })
});

And the second function outputs the same. Why is this happening?

Answer 1

Your alert returns the length of the string p#ancho_ventana, which contains 15 characters.
I think you meant:

alert($('p#ancho_ventana').length);