如何通过“显示全部/无”按钮使之工作？

function popupD1() {
    var popup = document.getElementById("myPopupD1");
    popup.classList.toggle("show");
    var image = document.getElementById("arrow1");
                    
    if (image.getAttribute('src') == "arrow.png") {
        image.src = "arrowL.png";
    } else {
        image.src = "arrow.png";
    }
    				
    var D1S = document.getElementById("D1S");
    if (D1S.textContent == "Show info"){
        D1S.textContent = "Hide info";
    } else {
        D1S.textContent="Show info";
    }
}

function D1moreinfo() {
    var hide = document.getElementById("D1moreinfo");
    if (hide.style.display ==="block"){
        hide.style.display = "none";
    } else {
        hide.style.display = "block";
    }
    
    var image =  document.getElementById("arrowL1");
    if (image.getAttribute('src') == "arrowL.png") {
        image.src = "arrow.png";
    } else {
        image.src = "arrowL.png";
    }
}
    
function popupD2() {
    var popup = document.getElementById("myPopupD2");
    popup.classList.toggle("show");
    var image = document.getElementById("arrow1");
    if (image.getAttribute('src') == "arrow.png") {
        image.src = "arrowL.png";
    } else {
        image.src = "arrow.png";
    }
    				
    var D1S=document.getElementById("D2S");
    if (D1S.textContent == "Show info") {
        D1S.textContent = "Hide info";
    } else {
        D1S.textContent = "Show info";
    }
}
    
function D2moreinfo(){
    var hide=document.getElementById("D2moreinfo");
    if (hide.style.display ==="block"){
        hide.style.display="none";
    } else {
        hide.style.display="block";
    }
    	
    var image = document.getElementById("arrowL1");
    if (image.getAttribute('src') == "arrowL.png") {
        image.src = "arrow.png";
    } else {
        image.src = "arrowL.png";
    }
}
    
function showall() {
    var D1 = document.getElementById("myPopupD1");
    var D2 = document.getElementById("myPopupD2");
    var D1M = document.getElementById("D1moreinfo");
    var D2M = document.getElementById("D2moreinfo");
    // First we check if all elements are showing
    var allShowing = (D1.classList.contains("show") && 
                    D2.classList.contains("show"));
    // Then we allways hide the elements
    D1.classList.remove("show");
    D2.classList.remove("show");
    // If any element was hidden, we show all of them
    if (!allShowing) {
        D1.classList.add("show");
        D2.classList.add("show");
    }
    
    if (D1M.style.display === "block") {
        D1M.style.display = "none";
    } else {
        D1M.style.display = "block";
    }

    if (D2M.style.display ==="block") {
        D2M.style.display="none";
    } else {
        D2M.style.display="block";
    }
}
    

.D1 {  
    border: 1px solid;
    border-color: red;
    width: 450px;
    height: 220px;
    margin-top: 10px;
}

#D1button {
    border: none;
    overflow: hidden;
    background-color: transparent;
    display: block;
    position: absolute;
    left: 390px;
    top: 175px;
    color: red;
}

.popupD1 {
    position: relative;
    display: inline-block;
    cursor: pointer;
}

.popupD1 .popuptextD1 {
    visibility: hidden;
    width: 250px;
    height: 210px;
    color: red;
    text-align: center;
    border-radius: 6px;
    padding: 8px 0;
    left: 370px;
    position: absolute;
    z-index: 0;
    top: 20px;
    background-color: gray;
    margin-left: 100px;
}

.popupD1 .popuptextD1:hover {
    transition: 1.5s;
    background-image: url(BF4B9.jpg);
    color: red;
}

.popupD1 .show {
    visibility: visible;
    -webkit-animation: fadeIn;
    animation: fadeIn 1s;
}

#D1moreinfo {
    background-color: transparent;
    border-radius: 6px;
    width: 200px;
    height: relative;
    display: none;
    position: absolute;
    top: -5px;
    left: 255px;
}
  
.D2 {  
    border: 1px solid;
    border-color: red;
    width: 450px;
    height: 220px;
    margin-top: 10px;
}

#D2button {
    border: none;
    overflow: hidden;
    background-color: transparent;
    display: block;
    position: absolute;
    left: 390px;
    top: 290px;
    color: red;
}

.popupD2 {
    position: relative;
    display: inline-block;
    cursor: pointer;
}

.popupD2 .popuptextD2 {
    visibility: hidden;
    width: 250px;
    height: 210px;
    color: red;
    text-align: center;
    border-radius: 6px;
    padding: 8px 0;
    left: 370px;
    position: absolute;
    z-index: 0;
    top: 20px;
    background-color: gray;
    margin-left: 100px;
}

.popupD2 .popuptextD2:hover {
    transition: 1.5s;
    background-image: url(BF4B9.jpg);
    color: red;
}

.popupD2 .show {
    visibility: visible;
    -webkit-animation: fadeIn;
    animation: fadeIn 1s;
}

#D2moreinfo {
    background-color: transparent;
    border-radius: 6px;
    width: 200px;
    height: relative;
    display: none;
    position: absolute;
    top: -5px;
    left: 255px;
}

.showall {
    overflow: hidden;
    background-color: transparent;
    position: absolute;
    top: -4px;
    left: 335px;
    position: fixed;
    border-radius: 10px;
}

<div class="D1">
    <div class="popupD1">
        <span class="popuptextD1" id="myPopupD1">
             *A long text that I'm not gonna paste here*
            <br/>
            <button id="morebutton1" onclick="D1moreinfo()">
                <img id="arrowL1" src="arrow.png"/>
            </button>
            <div id="D1moreinfo">
                <ul>
                    <li>XY</li>
                    <li>XY</li>
                    <li>XY</li>
                    <li>XY</li>
                    <li>XY</li>
                    <li>XY</li>
                    <li>XY</li>
                    <li>XY</li>
                </ul>
            </div>
        </span>
    </div>
    <img id="D1K" src="XY.png"/>
    <button id="D1button" onclick="popupD1()">
        <img id="arrow1" src="arrow.png"/>
        <br/>
        <span id="D1S">Show info</span>
    </button>
</div>

<div class="D2">
    <div class="popupD2">
        <span class="popuptextD2" id="myPopupD2">
            *A long text that I'm not gonna paste here*<br>
            <button id="morebutton1" onclick="D2moreinfo()">
                <img id="arrowL1" src="arrow.png"/>
            </button>
            <div id="D2moreinfo">
                <ul>
                    <li>XY</li>
                    <li>XY</li>
                    <li>XY</li>
                    <li>XY</li>
                    <li>XY</li>
                    <li>XY</li>
                    <li>XY</li>
                    <li>XY</li>
                </ul>
            </div>
        </span>
    </div>
    <img id="D2K" src="XY.png"/>
    <button id="D2button" onclick="popupD2()">
        <img id="arrow1" src="arrow.png"/>
        <br/>
        <span id="D2S">Show info</span>
    </button>
</div>

<div class="showall">
    <button onclick="showall()" title="Hide/show all">
        <span id="show">Show all</span>
    </button>
</div>