javascript - 当覆盖处于事件状态时，网页的滚动应该可见

Question

目标:
当您打开叠加层时，网页的滚动条(不是叠加层的滚动条)应该可见但不能使用。

问题:
当您看到滚动条不可见时页面移动到右侧，而当您看到滚动条时页面移动到与叠加层相关的右侧，这让人很恼火。

有办法吗？

谢谢!

function openNav() {
    document.getElementById("myNav").style.height = "100%";
    
     $('body').addClass('noscroll');   
}

function closeNav() {
    document.getElementById("myNav").style.height = "0%";
    
     $('body').removeClass('noscroll');
    
}

body {
    margin: 0;
    font-family: 'Lato', sans-serif;
}

.overlay {
    height: 0%;
    width: 100%;
    position: fixed;
    z-index: 1;
    top: 0;
    left: 0;
    background-color: rgb(0,0,0);
    background-color: rgba(0,0,0, 0.8);
    overflow-y: hidden;
    transition: 0.5s;
}

.overlay-content {
   position: relative;
   top: 10%;
   width: 70%;
   text-align: left;
   margin: 30px auto;
   background: white;
    overflow-y: auto;
    height: 100%;  
    
}

.overlay a {
    padding: 8px;
    text-decoration: none;
    font-size: 36px;
    color: #818181;
    display: block;
    transition: 0.3s;
}

.overlay a:hover, .overlay a:focus {
    color: #f1f1f1;
}

.overlay .closebtn {
    position: absolute;
    top: 20px;
    right: 45px;
    font-size: 60px;
}


.noscroll { 
  overflow: hidden;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="myNav" class="overlay">
  <a href="javascript:void(0)" class="closebtn" onclick="closeNav()">&times;</a>
  <div class="overlay-content">
    <a href="#">About</a>
    <a href="#">Services</a>
    <a href="#">Clients</a>
    <a href="#">Contact</a>
    <a href="#">About</a>
    <a href="#">Services</a>
    <a href="#">Clients</a>
    <a href="#">Contact</a>
    <a href="#">About</a>
    <a href="#">Services</a>
    <a href="#">Clients</a>
    <a href="#">Contact</a>
    <a href="#">Services</a>
    <a href="#">Clients</a>
    <a href="#">Contact</a>
    
    <a href="#">About</a>
    <a href="#">Services</a>        
    <a href="#">About</a>
    <a href="#">Services</a>
    <a href="#">Clients</a>
    <a href="#">CANDY</a>    
  </div>
</div>

<h2>Fullscreen Overlay Nav Example</h2>
<p>Click on the element below to open the fullscreen overlay navigation menu.</p>
<p>In this example, the navigation menu will slide downwards from the top:</p>
  
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<span style="font-size:30px;cursor:pointer" onclick="openNav()">&#9776; open</span>  

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Answer 1

只需将“position: fixed; overflow-y:scroll”添加到你的无滚动类。

如果你不希望它到顶部，根据主体的当前滚动获取当前的 X 位置并将 Y 偏移设置为该值

function openNav() {
    document.getElementById("myNav").style.height = "100%";
    $(document).scrollTop()
     $('body').addClass('noscroll');   

}

function closeNav() {
    document.getElementById("myNav").style.height = "0%";
    
     $('body').removeClass('noscroll');
$('body').scroll(function() { alert("scroll") });
    
}

body {
    margin: 0;
    font-family: 'Lato', sans-serif;
    overflow-y: scroll;

}

.overlay {
    height: 0%;
    width: 100%;
    position: fixed;
    z-index: 1;
    top: 0;
    left: 0;
    background-color: rgb(0,0,0);
    background-color: rgba(0,0,0, 0.8);
    overflow-y: hidden;
    transition: 0.5s;
}

.overlay-content {
   position: relative;
   top: 10%;
   width: 70%;
   text-align: left;
   margin: 30px auto;
   background: white;
    overflow-y: auto;
    height: 100%;  
    
}

.overlay a {
    padding: 8px;
    text-decoration: none;
    font-size: 36px;
    color: #818181;
    display: block;
    transition: 0.3s;
}

.overlay a:hover, .overlay a:focus {
    color: #f1f1f1;
}

.overlay .closebtn {
    position: absolute;
    top: 20px;
    right: 45px;
    font-size: 60px;
}


.noscroll { 
  position: fixed; overflow-y:scroll;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="myNav" class="overlay">
  <a href="javascript:void(0)" class="closebtn" onclick="closeNav()">&times;</a>
  <div class="overlay-content">
    <a href="#">About</a>
    <a href="#">Services</a>
    <a href="#">Clients</a>
    <a href="#">Contact</a>
    <a href="#">About</a>
    <a href="#">Services</a>
    <a href="#">Clients</a>
    <a href="#">Contact</a>
    <a href="#">About</a>
    <a href="#">Services</a>
    <a href="#">Clients</a>
    <a href="#">Contact</a>
    <a href="#">Services</a>
    <a href="#">Clients</a>
    <a href="#">Contact</a>
    
    <a href="#">About</a>
    <a href="#">Services</a>        
    <a href="#">About</a>
    <a href="#">Services</a>
    <a href="#">Clients</a>
    <a href="#">CANDY</a>    
  </div>
</div>

<h2>Fullscreen Overlay Nav Example</h2>
<p>Click on the element below to open the fullscreen overlay navigation menu.</p>
<p>In this example, the navigation menu will slide downwards from the top:</p>
  
<br/>  
<br/>  
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<span style="font-size:30px;cursor:pointer" onclick="openNav()">&#9776; open</span>  

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