javascript - 当用户向下滚动时为图表制作动画

Question

我有一个关于 CSS3 和 JavaScript 的问题。我想让那些图表栏在用户滚动时显示动画吗？现在它在页面加载后动画 500 毫秒。我想在用户滚动时启动图表栏动画。但是，我不知道如何检测特定图表是否对用户可见。

setTimeout(function start() {

    $('.bar').each(function (i) {
        var $bar = $(this);
        $(this).append('<span class="count"></span>')
        setTimeout(function () {
            $bar.css('width', $bar.attr('data-percent'));
        }, i * 100);
    });

    $('.count').each(function () {
        $(this).prop('Counter', 0).animate({
            Counter: $(this).parent('.bar').attr('data-percent')
        }, {
            duration: 2000,
            easing: 'swing',
            step: function (now) {
                $(this).text(Math.ceil(now) + '%');
            }
        });
    });

}, 500)

@import url(http://fonts.googleapis.com/css?family=Droid+Serif:400, 400italic|Montserrat:400, 700);
 html, body, div, span, applet, object, iframe, h1, h2, h3, h4, h5, h6, p, blockquote, pre, a, abbr, acronym, address, big, cite, code, del, dfn, em, img, ins, kbd, q, s, samp, small, strike, strong, sub, sup, tt, var, b, u, i, center, dl, dt, dd, ol, ul, li, fieldset, form, label, legend, table, caption, tbody, tfoot, thead, tr, th, td, article, aside, canvas, details, embed, figure, figcaption, footer, header, hgroup, menu, nav, output, ruby, section, summary, time, mark, audio, video {
    margin: 0;
    padding: 0;
    border: 0;
    font: inherit;
    font-size: 100%;
    vertical-align: baseline;
}
html {
    line-height: 1;
}
ol, ul {
    list-style: none;
}
table {
    border-collapse: collapse;
    border-spacing: 0;
}
caption, th, td {
    text-align: left;
    font-weight: normal;
    vertical-align: middle;
}
q, blockquote {
    quotes: none;
}
q:before, q:after, blockquote:before, blockquote:after {
    content:"";
    content: none;
}
a img {
    border: none;
}
article, aside, details, figcaption, figure, footer, header, hgroup, main, menu, nav, section, summary {
    display: block;
}
* {
    box-sizing: border-box;
}
body {
    color: #333;
    -webkit-font-smoothing: antialiased;
    font-family:"Montserrat", sans-serif;
    padding: 2%;
}
.wrap {
    width: 50%;
    margin: 0 auto;
}
h1 {
    font-family:"Montserrat", sans-serif;
    font-weight: bold;
    text-align: center;
    font-size: 1.5em;
    padding: .5em 0;
    margin-bottom: 1em;
    border-bottom: 1px solid #dadada;
    letter-spacing: 3px;
    text-transform: uppercase;
}
ul li {
    line-height: 2;
    font-weight: bold;
    font-family:"Montserrat", sans-serif;
    font-size: .85em;
    text-transform: uppercase;
    clear: both;
}
ul li:before {
    content:"\2023";
    padding: 0 1em 0 0;
}
.bar {
    background: #e74c3c;
    width: 0;
    margin: .25em 0;
    color: #fff;
    position: relative;
    transition: width 2s, background .2s;
    clear: both;
}
.bar:nth-of-type(2n) {
    background: #ed7669;
}
.bar .label {
    font-size: .75em;
    padding: 1em;
    background: #3d3d3d;
    width: 8em;
    display: inline-block;
    position: relative;
    z-index: 2;
    font-weight: bold;
    font-family:"Montserrat", sans-serif;
}
.bar .label.light {
    background: #575757;
}
.count {
    position: absolute;
    right: .25em;
    top: .75em;
    padding: .15em;
    font-size: .75em;
    font-weight: bold;
    font-family:"Montserrat", sans-serif;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="wrap">
     <h1>Animated Bar Graphs</h1>

    <div class="holder">
        <div class="bar cf" data-percent="85%"><span class="label">Photoshop</span>
        </div>
        <div class="bar cf" data-percent="75%"><span class="label light">Illustrator</span>
        </div>
        <div class="bar cf" data-percent="65%"><span class="label">Indesign</span>
        </div>
        <div class="bar cf" data-percent="90%"><span class="label light">HTML</span>
        </div>
        <div class="bar cf" data-percent="90%"><span class="label">CSS</span>
        </div>
        <div class="bar cf" data-percent="80%"><span class="label light">jQuery</span>
        </div>
        <div class="bar cf" data-percent="85%"><span class="label light">RWD</span>
        </div>
        <div class="bar cf" data-percent="75%"><span class="label">PHP</span>
        </div>
        <div class="bar cf" data-percent="80%"><span class="label light">WordPress</span>
        </div>
        <div class="bar cf" data-percent="70%"><span class="label">SASS/SCSS</span>
        </div>
    </div>
</div>

Answer 1

这就是你要找的:

$(window).scroll(function() {
    if ($(this).scrollTop() >= $('.holder').offset().top) {
        ...
    }
});

当您的 window 对象的 scrollTop 位于您的购物车的开头时，这将调用动画，因此它确保，以防您的购物车位于最底部确保动画在正确的时间激活，不会太早也不会太晚。

$(window).scroll(function() {
    if ($(this).scrollTop() >= $('.holder').offset().top) {
        $('.bar').each(function(i) {
            var $bar = $(this);
            $(this).append('<span class="count"></span>')
            setTimeout(function() {
                $bar.css('width', $bar.attr('data-percent'));
            }, i * 100);
        });

        $('.count').each(function() {
            $(this).prop('Counter', 0).animate({
                Counter: $(this).parent('.bar').attr('data-percent')
            }, {
                duration: 2000,
                easing: 'swing',
                step: function(now) {
                    $(this).text(Math.ceil(now) + '%');
                }
            });
        });
    }
})

@import url(http://fonts.googleapis.com/css?family=Droid+Serif:400, 400italic|Montserrat:400, 700);
 html, body, div, span, applet, object, iframe, h1, h2, h3, h4, h5, h6, p, blockquote, pre, a, abbr, acronym, address, big, cite, code, del, dfn, em, img, ins, kbd, q, s, samp, small, strike, strong, sub, sup, tt, var, b, u, i, center, dl, dt, dd, ol, ul, li, fieldset, form, label, legend, table, caption, tbody, tfoot, thead, tr, th, td, article, aside, canvas, details, embed, figure, figcaption, footer, header, hgroup, menu, nav, output, ruby, section, summary, time, mark, audio, video {
    margin: 0;
    padding: 0;
    border: 0;
    font: inherit;
    font-size: 100%;
    vertical-align: baseline;
}
html {
    line-height: 1;
}
ol, ul {
    list-style: none;
}
table {
    border-collapse: collapse;
    border-spacing: 0;
}
caption, th, td {
    text-align: left;
    font-weight: normal;
    vertical-align: middle;
}
q, blockquote {
    quotes: none;
}
q:before, q:after, blockquote:before, blockquote:after {
    content:"";
    content: none;
}
a img {
    border: none;
}
article, aside, details, figcaption, figure, footer, header, hgroup, main, menu, nav, section, summary {
    display: block;
}
* {
    box-sizing: border-box;
}
body {
    color: #333;
    -webkit-font-smoothing: antialiased;
    font-family:"Montserrat", sans-serif;
    padding: 2%;
}
.wrap {
    width: 50%;
    margin: 0 auto;
}
h1 {
    font-family:"Montserrat", sans-serif;
    font-weight: bold;
    text-align: center;
    font-size: 1.5em;
    padding: .5em 0;
    margin-bottom: 1em;
    border-bottom: 1px solid #dadada;
    letter-spacing: 3px;
    text-transform: uppercase;
}
ul li {
    line-height: 2;
    font-weight: bold;
    font-family:"Montserrat", sans-serif;
    font-size: .85em;
    text-transform: uppercase;
    clear: both;
}
ul li:before {
    content:"\2023";
    padding: 0 1em 0 0;
}
.bar {
    background: #e74c3c;
    width: 0;
    margin: .25em 0;
    color: #fff;
    position: relative;
    transition: width 2s, background .2s;
    clear: both;
}
.bar:nth-of-type(2n) {
    background: #ed7669;
}
.bar .label {
    font-size: .75em;
    padding: 1em;
    background: #3d3d3d;
    width: 8em;
    display: inline-block;
    position: relative;
    z-index: 2;
    font-weight: bold;
    font-family:"Montserrat", sans-serif;
}
.bar .label.light {
    background: #575757;
}
.count {
    position: absolute;
    right: .25em;
    top: .75em;
    padding: .15em;
    font-size: .75em;
    font-weight: bold;
    font-family:"Montserrat", sans-serif;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="wrap">
     <h1>Animated Bar Graphs</h1>

    <div class="holder">
        <div class="bar cf" data-percent="85%"><span class="label">Photoshop</span>
        </div>
        <div class="bar cf" data-percent="75%"><span class="label light">Illustrator</span>
        </div>
        <div class="bar cf" data-percent="65%"><span class="label">Indesign</span>
        </div>
        <div class="bar cf" data-percent="90%"><span class="label light">HTML</span>
        </div>
        <div class="bar cf" data-percent="90%"><span class="label">CSS</span>
        </div>
        <div class="bar cf" data-percent="80%"><span class="label light">jQuery</span>
        </div>
        <div class="bar cf" data-percent="85%"><span class="label light">RWD</span>
        </div>
        <div class="bar cf" data-percent="75%"><span class="label">PHP</span>
        </div>
        <div class="bar cf" data-percent="80%"><span class="label light">WordPress</span>
        </div>
        <div class="bar cf" data-percent="70%"><span class="label">SASS/SCSS</span>
        </div>
    </div>
</div>