Extract only the numbers from a Javascript text box

You can filter the value of the field:

var valor_extraido = valor_extraido.replace(/[^0-9]/g,'');

You can use the regular expression to replace all non-numeric characters, this is represented by \D , g at the end means that substitution is done on all found elements by default (without g ) only a replacement is done.

"1a321q00".replace(/\D/g, "")

You can set the input with type number :

<input type="number" />

Detail is that the and character can be used because it means exponentiation .