苹果iphone ios系统 键盘弹起导致页面高度发生变化，无法

document.body.addEventListener('focusin', () => {  //软键盘弹起事件
        var scrollTop = 0;
        if (document.documentElement && document.documentElement.scrollTop) {
            scrollTop = document.documentElement.scrollTop;
        } else if (document.body) {
            scrollTop = document.body.scrollTop;
        }
        window.workrelateScrollTop = scrollTop
    });
    document.body.addEventListener('focusout', () => { //软键盘关闭事件
        var ua = window.navigator.userAgent;
        if (ua.indexOf('iPhone') > 0 || ua.indexOf('iPad') > 0) { //键盘收起页面空白问题
            document.body.scrollTop = window.workrelateScrollTop;
            document.documentElement.scrollTop = window.workrelateScrollTop;
        }
    });