需要时水平滚动列表中心

Question

单击列表中的链接时，我必须移动水平导航栏。我创建了一个JSFiddle来说明我的问题。

当用户点击列表中的链接时，列表需要向左或向右滚动。这部分已经完成。

当您点击链接时，活动链接需要在列表中居中。

链接到JSFiddle： https://jsfiddle.net/7yq0jq9s/2/

HTML

<div class="container">
<ul>
    <li class="active"> <a href="#">1</a>

    </li>
    <li> <a href="#">2</a>

    </li>
    <li> <a href="#">3</a>

    </li>
    <li> <a href="#">4</a>

    </li>
    <li> <a href="#">5</a>

    </li>
    <li> <a href="#">6</a>

    </li>
    <li> <a href="#">7</a>

    </li>
    <li> <a href="#">8</a>

    </li>
</ul>

CSS

div.container {
    width: 600px;
    overflow: hidden;
}

ul {
    white-space: nowrap;
}

ul li {
    display: inline-block;
    background: green;
}

ul li a {
    padding: 80px;
    display: block;
    color: white;
    font-weight: bold;
    text-decoration: none;
}

ul li.active {
    background: blue;

}

JS

$(document).ready(function () {
var scrollTo = 0;
$('body').on('click', "a", function () {
    var activeItem = $('li.active');
    var selectedItem = $(this).parent()

    var activeIndex = $('li').index(activeItem);
    var selectedIndex = $('li').index(selectedItem);

    if (selectedIndex > activeIndex) {
        scrollTo -= selectedItem.position().left - activeItem.position().left;
        console.log('Scroll right');
    } else {
        scrollTo += Math.abs(selectedItem.position().left - activeItem.position().left);
        console.log('Scroll left');
        if (scrollTo >= 0) {
            scrollTo = 0;
        }
    }

    $('ul').css('transform', 'translateX(' + scrollTo + 'px)');
    activeItem.removeClass('active');
    selectedItem.addClass('active');

});
});

Answer 1

我认为更容易获得点击元素的绝对位置并计算容器的中间位置，而不是检查它是否需要向左或向右滚动：

＆＃13;

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    var scrollTo = 0;
    $('body').on('click', "a", function () {
        var activeItem = $('li.active');
        var selectedItem = $(this).parent()

        var activeIndex = $('li').index(activeItem);
        var selectedIndex = $('li').index(selectedItem);
        
        scrollTo =- selectedItem.position().left + $('.container').width() / 2 - selectedItem.width() / 2;

        $('ul').css('transform', 'translateX(' + scrollTo + 'px)');
        activeItem.removeClass('active');
        selectedItem.addClass('active');

    });

＆＃13;

div.container {

    width: 600px;

    overflow: hidden;

}

ul {

    white-space: nowrap;
    transition: all ease 750ms;
    position:relative;
}

ul li {

    display: inline-block;

    background: green;

}

ul li a {

    padding: 80px;

    display: block;

    color: white;

    font-weight: bold;

    text-decoration: none;

}

ul li.active {

    background: blue;

}

＆＃13;

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<div class="container">
    <ul>
        <li class="active"> <a href="#">1</a>

        </li>
        <li> <a href="#">2</a>

        </li>
        <li> <a href="#">3</a>

        </li>
        <li> <a href="#">4</a>

        </li>
        <li> <a href="#">5</a>

        </li>
        <li> <a href="#">6</a>

        </li>
        <li> <a href="#">7</a>

        </li>
        <li> <a href="#">8</a>

        </li>
    </ul>
</div>

＆＃13;

＆＃13;

＆＃13;

Answer 2

我认为你只需要在第10行改变一点：

if (selectedIndex = activeIndex) {

https://jsfiddle.net/7yq0jq9s/3/

Answer 3

＆＃13;

＆＃13;

    var scrollTo = 0;
    $('body').on('click', "a", function () {
        var activeItem = $('li.active');
        var selectedItem = $(this).parent()

        var activeIndex = $('li').index(activeItem);
        var selectedIndex = $('li').index(selectedItem);
        
        scrollTo =- selectedItem.position().left + $('.container').width() / 2 - selectedItem.width() / 2;

        $('ul').css('transform', 'translateX(' + scrollTo + 'px)');
        activeItem.removeClass('active');
        selectedItem.addClass('active');

    });

＆＃13;

div.container {

    width: 600px;

    overflow: hidden;

}

ul {

    white-space: nowrap;
    transition: all ease 750ms;
    position:relative;
}

ul li {

    display: inline-block;

    background: green;

}

ul li a {

    padding: 80px;

    display: block;

    color: white;

    font-weight: bold;

    text-decoration: none;

}

ul li.active {

    background: blue;

}

＆＃13;

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<div class="container">
    <ul>
        <li class="active"> <a href="#">1</a>

        </li>
        <li> <a href="#">2</a>

        </li>
        <li> <a href="#">3</a>

        </li>
        <li> <a href="#">4</a>

        </li>
        <li> <a href="#">5</a>

        </li>
        <li> <a href="#">6</a>

        </li>
        <li> <a href="#">7</a>

        </li>
        <li> <a href="#">8</a>

        </li>
    </ul>
</div>

＆＃13;

＆＃13;

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