Using attr() to set value of an input field breaks reading the value out of it

While the slider is the only one setting the value of the input with `input.attr("value", ...)`, other scripts can read out the correct value with either `input.get(0).value` or `input.val()`, but as soon as some other script modifies the value of the input with `.prop("value", ...)` or `.val(...)`, the updates from the slider are no longer readable with `.val()` getter. Instead, the value before the overwrite with `.prop("value", ...)` or `.val(...)` is always returned.