“Получите нижнее положение элемента JavaScript” Ответ

Получите нижнее положение элемента JavaScript

window.innerHeight - (window.scrollY + document.querySelector('myID').getBoundingClientRect().top+document.getElementById('myID'). offsetHeight)
//I assume this means distance from bottom of an element to the bottom of the window
//Basically getting the window height, then subtracting the item height and  the height from the top.