Onscroll 导航栏无法正常工作在移动设备上点击汉堡菜单时它会向上移动

如何解决Onscroll 导航栏无法正常工作在移动设备上点击汉堡菜单时它会向上移动

<nav id="mynav" class="navbar navbar-expand-lg navbar-light sticky-top">
        <div id="mainnav" class="container-fluid" >
                <a class="navbar-brand pt-0 pb-0" href="index.html">
                    <img src="./assets/pranav logo1 (1).png" class="img-fluid d-inline-block align-top logo" alt="" loading="lazy">
                </a>
    
                <button class="navbar-toggler mr-5" id="mynavbtn" type="button" data-toggle="collapse" data-target="#navbarNavDropdown" aria-controls="navbarNavDropdown" aria-expanded="false" aria-label="Toggle navigation">
                  <span class="navbar-toggler-icon"></span>
                </button>
                <div class="collapse navbar-collapse mob" id="navbarNavDropdown">
                  <ul class="navbar-nav">
                    <li class="nav-item active">
                      <a class="nav-link js-scroll-trigger" href="index.html">Home <span class="sr-only">(current)</span></a>
                    </li>
                    <li class="nav-item">
                      <a class="nav-link js-scroll-trigger" href="about.html">About</a>
                    </li>
                    
                    <li class="nav-item dropdown">
                      <a class="nav-link dropdown-toggle" href="services.html" id="navbarDropdownMenuLink" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
                        Services
                      </a>
                      <div class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
                        <a class="dropdown-item js-scroll-trigger" href="services.html">Web Designing</a>
                        <a class="dropdown-item js-scroll-trigger" href="services.html">Software Development</a>
                        <a class="dropdown-item js-scroll-trigger" href="services.html">Digital Marketing</a>
                      </div>
                    </li>
    
                    <li class="nav-item">
                        <a class="nav-link js-scroll-trigger" href="portfolio.html">Portfolio</a>
                      </li>
                      <li class="nav-item">
                        <a class="nav-link js-scroll-trigger" href="contact-us.html">Contact</a>
                      </li>
    
    
                  </ul>
                </div>
              
           
        </div>
        </nav> 


$(document).ready(function(){
    var backScroll =window.pageYOffset;
    window.onscroll = function (){
        var currentScroll = window.pageYOffset;
        if(backScroll >currentScroll) {
            document.getElementById("mynav").style.top="0";
        }else{
            document.getElementById("mynav").style.top="-100px";

        }
        backScroll = currentScroll;
    }
    
});

(Wrong Output)The navbar is hidden (top:-100px)

Expected Output

当检测到向下滚动时导航栏被隐藏（顶部：100px）并且当检测到向上滚动时导航栏将显示但在移动设备中当我点击汉堡菜单时它会折叠但也隐藏徽标和汉堡部分时，在桌面上代码正常工作. 我上传了，你会收到的。