javascript - 只有 10 个可见链接的下拉菜单

Question

所以，我想知道是否可以使下拉菜单只有 10 个可见链接，而其余的则不可见。如果不可能，是否可以做到这样，您只能选择 10 并向下滚动。有什么建议吗？

function myFunction() {
    document.getElementById("myDropdown").classList.toggle("show");
}

function filterFunction() {
    var input, filter, ul, li, a, i;
    input = document.getElementById("myInput");
    filter = input.value.toUpperCase();
    div = document.getElementById("myDropdown");
    a = div.getElementsByTagName("a");
    for (i = 0; i < a.length; i++) {
        if (a[i].innerHTML.toUpperCase().indexOf(filter) > -1) {
            a[i].style.display = "";
        } else {
            a[i].style.display = "none";
        }
    }
}

.dropbtn {
    background-color: #4CAF50;
    color: white;
    padding: 16px;
    font-size: 16px;
    border: none;
    cursor: pointer;
}

.dropbtn:hover, .dropbtn:focus {
    background-color: #3e8e41;
}
#myInput {
    border-box: box-sizing;
    background-image: url('searchicon.png');
    background-position: 14px 12px;
    background-repeat: no-repeat;
    font-size: 16px;
    padding: 14px 20px 12px 45px;
    border: none;
}

.dropdown {
    position: relative;
    display: inline-block;
}

.dropdown-content {
    display: none;
    position: absolute;
    background-color: #f6f6f6;
    min-width: 230px;
    overflow: auto;
    box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
    z-index: 1;
}

.dropdown-content a {
    color: black;
    padding: 12px 16px;
    text-decoration: none;
    display: block;
}

.dropdown a:hover {background-color: #ddd}

.show {display:block;}

<div class="dropdown">
<button onclick="myFunction()" class="dropbtn">Dropdown</button>
  <div id="myDropdown" class="dropdown-content">
    <input type="text" placeholder="Search.." id="myInput" onkeyup="filterFunction()">
    <a href="#about">About</a>
    <a href="#base">Base</a>
    <a href="#blog">Blog</a>
    <a href="#contact">Contact</a>
    <a href="#custom">Custom</a>
    <a href="#support">Support</a>
    <a href="#tools">Tools</a>
    <a href="#about">About</a>
    <a href="#base">Base</a>
    <a href="#blog">Blog</a>
    <a href="#contact">Contact</a>
    <a href="#custom">Custom</a>
    <a href="#support">Support</a>
    <a href="#tools">Tools</a>
    <a href="#about">About</a>
    <a href="#base">Base</a>
    <a href="#blog">Blog</a>
    <a href="#contact">Contact</a>
    <a href="#custom">Custom</a>
    <a href="#support">Support</a>
    <a href="#tools">Tools</a>
  </div>
</div>

Answer 1

编辑:新答案:

我误解了这个问题。您可以稍微修改过滤器函数以跟踪显示的项目 (10)，然后在打开菜单时调用它一次。这样，您在打开菜单和过滤时最多可以显示 10 个项目。 fiddle :https://jsfiddle.net/d3kta5sw/

function myFunction() {
    document.getElementById("myDropdown").classList.toggle("show");
    filterFunction();
}

function filterFunction() {
    var input, filter, ul, li, a, i,
        elementsToShow = 10,
        elementsShowing = 0;

    input = document.getElementById("myInput");
    filter = input.value.toUpperCase();
    div = document.getElementById("myDropdown");
    a = div.getElementsByTagName("a");

    for (i = 0; i < a.length; i++) {
        if (a[i].innerHTML.toUpperCase().indexOf(filter) > -1 &&
            elementsShowing < elementsToShow) {
            a[i].style.display = "";
            elementsShowing++;
        } else {
            a[i].style.display = "none";
        }
    }
}

旧答案(仅适用于前 10 个可见项目):

你可以用纯 CSS 来做到这一点。尝试添加以下内容，这将隐藏第 11 个“a”元素及以后的元素:

.dropdown-content a:nth-of-type(n+11) {
  display:none;
}