Save and restore the text selection

// Save the selection
// Return a `Range` instance if there is a selected text
const save = function () {
    const selection = window.getSelection();
    return selection.rangeCount === 0 ? null : selection.getRangeAt(0);
};

// Restore the selection
// `range` is a `Range` object
const restore = function (range) {
    const selection = window.getSelection();
    selection.removeAllRanges();
    selection.addRange(range);
};