Input value doesn't display. How is that possible?

Question

This must be something utterly stupid that I\'ve done or am doing, but I have an input with a value attribute that simply isn\'t being displayed:

Answer 1

I had the same problem of @Rob Wilkerson, a onchange() was cleaning the value of the input with "", so i changed to 1. Such a dumb problem!

HTML

Jquery
$("#txtNumIntervalo").val(1);