how do i get the bottom offset of a scroll div from windowheight : Please  see img the height i want from the reb box div bottom offset from window [See image for refrence][1]

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    //want offset bottom of box  after some scroll of body scroll

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    .divHasScroll{height:200px; width:350px; background:red; overflow:auto}

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    <div class="divHasScroll">
    <p> text in box</p><p> text in box</p><p> text in box</p><p> text in box</p><p> text in box</p><p> text in box</p><p> text in box</p><p> text in box</p><p> text in box</p><p> text in box</p><p> text in box</p>
    </div>

    <p> text in window scrolling section</p><p> text in window scrolling section</p><p> text in window scrolling section</p><p> text in window scrolling section</p><p> text in window scrolling section</p><p> text in window scrolling section</p><p> text in window scrolling section</p><p> text in window scrolling section</p><p> text in window scrolling section</p><p> text in window scrolling section</p><p> text in window scrolling section</p><p> text in window scrolling section</p><p> text in window scrolling section</p><p> text in window scrolling section</p>

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  [1]: https://i.stack.imgur.com/lVsGb.jpg