There is a little code, I made it with the help of another topic and with a little thought with my head.
var a=(document.getElementsByName("products_qty").value); document.write(a);
This variable is written to the value entered in the input field. And how I would like (for a long time to explain) that this same value be duplicated elsewhere on the page. Ie I change the value in the input field - the value of the variable a also changes.
Probably, you can somehow push off from the fact that the input knows such a chip as a trick. Those. It seems to me that you can somehow force the value to change as soon as I stop typing numbers.