@uicapivara/cp-select/src/helpers/coordinates.ts

cp-select

export namespace Coordinates {
    export function get(el) {
        let xPos = 0, yPos = 0;
        while (el) {
            if (el.tagName == "BODY") {
                let xScroll = el.scrollLeft || document.documentElement.scrollLeft;
                let yScroll = el.scrollTop || document.documentElement.scrollTop;
                xPos += (el.offsetLeft - xScroll + el.clientLeft);
                yPos += (el.offsetTop - yScroll + el.clientTop);
            } else {
                xPos += (el.offsetLeft - el.scrollLeft + el.clientLeft);
                yPos += (el.offsetTop - el.scrollTop + el.clientTop);
            }
            el = el.offsetParent;
        }
        return {
            left: xPos,
            top: yPos
        };
    }
}