javascript scrollBy not scroll decimal numbers

Question

document.getElementById('idcardsliderScroll').scrollBy(399.4, 0 );
// result scroll 399px

and 

document.getElementById('idcardsliderScroll').scrollBy(399.5, 0 );
// result scroll 400px

I need to ScrollBy the decimal number without rounding, is it possible?

I don't know what to try

Answer 1

This is how the scrollBy( ) works. You can't do anything to change it.

syntax :

window.scrollBy({
  top: 100,
  left: 100,
  behavior: 'smooth'
});