Function handleChange

src/utils/Portal.tsx:126–134

()

    useLayoutEffect(() => {
        function handleChange() {
            let bcr = el ? el.getBoundingClientRect() : null;
            setBcr(prev => (el && prev) ? assignImm(prev, {
                x: includePosition ? bcr!.x : 0,
                y: includePosition ? bcr!.y : 0,
                width: bcr!.width,
                height: bcr!.height,
            }) : bcr);
        }

        if (el) {
            let observer = new ResizeObserver(handleChange);