JS-IOS输入法遮挡输入框解决办法

var focus = 0;
    var top = 0;
    $("#txt").on("focus",function () {
        //ios第一次弹出输入法遮住输入框解决方法
        setTimeout(function(){
            document.querySelector("#msg-input").scrollIntoView(true);
        },300);
        focus = 1;
        top = this.getBoundingClientRect().top;
        ios(this,top);

    });
    $("#txt").on("blur",function () {
        focus = 0;
    });

    //ios切换输入法遮住输入框解决方法
    function ios(dom,top) {
            setTimeout(function(){
                var newTop=dom.getBoundingClientRect().top;
                if(newTop !== top){
                    document.querySelector("#msg-input").scrollIntoView(true);
                    top=newTop;
                }
                if(focus===1){
                    ios(dom,top);
                }
            },200);
    }