Why does ie11 complain about these two features?

Question

JavaScript

$(document).on('mousemove', '.transfusionButton', function (event) {
            const buttonProportions = $(this)[0].getBoundingClientRect();
            const {
                clientX
            } = event;
            const {
                left
            } = buttonProportions;
            const x = clientX - left;
            const {
                width
            } = buttonProportions;

            $html.attr('style', `--transfusionPercent:${x - width / 2}px;`);
        });

function getCellsBy(cellIndex) {
            return $(`[data-cell-index=${cellIndex}]`);
        }

It says "Identifier is expected in this string":

const {
     clientX
} = event;

Answer 1

IE does not support destructuring assignment. Just like template strings.