[英]Vanilla JavaScript running CSS animation on div scroll into view not working
當div進入可見屏幕時,我正在嘗試運行CSS動畫。 但是,我注意到無論頁面如何加載,動畫都在播放。
我已經搜索了這個問題,弄亂了代碼,似乎沒有什么能給我正確的結果。
JavaScript的
var animateHTML = function() {
var elems;
var windowHeight;
function init() {
elems = document.querySelectorAll('.animatemeplz');
windowHeight = window.innerHeight;
addEventHandlers();
checkPosition();
}
function addEventHandlers() {
window.addEventListener('scroll', checkPosition);
window.addEventListener('resize', init);
}
function checkPosition() {
for (var i = 0; i < elems.length; i++) {
var positionFromTop = elems[i].getBoundingClientRect().top;
if (positionFromTop - windowHeight <= 0) {
elems[i].className = elems[i].className.replace(
'animatemeplz',
'animated fadeIn'
);
}
}
}
return {
init: init
};
};
animateHTML().init();
HTML
<div class="menu">
<div class="side-olay">
<p class="side-num">01</p>
<p class="side-nums">02</p>
<p class="side-nums">03</p>
<p class="side-nums">04</p>
</div>
</div>
<!-- START OF INITAL SCREEN -->
<div class="head rellax" data-rellax-speed="-10">
<img class="logo" src="img/logo.png">
<div class="ld1"></div>
<div class="ld2"></div>
<div class="ld3"></div>
<h3>SERVER <span style="font-weight: bold;">MOTTO</span></h3>
<p>Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor<br> incididunt ut ero labore et dolore.</p>
<p>Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor<br> incididunt ut ero labore et dolore.</p>
<div class="line"></div>
<a href="#" class="button1">Discord Server</a>
<img class="side" src="img/side.png">
</div>
<div class="stats">
<div class="chart animatemeplz">
<div class="chart-olay">
<ul>
<li>100</li>
<li>50</li>
<li>25</li>
<li>0</li>
</ul>
</div>
<img src="img/Group%2012.png">
<div class="chart-bar"></div>
<div class="chart-bar"></div>
<div class="chart-bar"></div>
<div class="chart-bar"></div>
<div class="chart-bar"></div>
<div class="chart-bar"></div>
<div class="chart-bar"></div>
<div class="chart-bar"></div>
</div>
<h1 class="h1 animatemeplz">STATISTICS</h1>
<p class="p1 animatemeplz">Lorem ipsum dolor sit amet,<br>consectetur adipsicing elit, sed do<br>eiusmod.</p>
<h1 class="h2 animatemeplz">FILTER</h1> <a class="filer-btn animatemeplz">Today</a><a class="filer-btn animatemeplz">A Month Ago</a><a class="filer-btn animatemeplz">4 Months Ago</a>
<p class="p2 animatemeplz">Filter our updated statistic log through clicking designated buttons to alter your filtered result.</p>
</div>
<div class="feat">
<div class="featside">
<div class="sidedot"></div>
<div class="sidedot2"></div>
<div class="sidedot3"></div>
</div>
<img class="featbg" src="img/featbg.png">
<h1>Features</h1>
<div class="line"></div>
<H1><span id="typed">Down to Roleplay ping-able role (@DTRP)</span></H1>
<!--<h1>Down to Roleplay ping-able role (@DTRP) </h1>-->
<p style="margin-left: 20vw;">pingable only every 3 hours or something #DM-request ping spam</p>
</div>
預期結果:將div滾動到視圖中時播放動畫。 實際結果:即使在div不可見的情況下,加載頁面時也會播放動畫。
這個問題似乎取決於您的CSS。 您的JavaScript .animatemeplz
進入視口的元素的.animate
和.fadeIn
類替換為.animatemeplz
類,因此以下形式的CSS應該確保動畫有效:
.animatemeplz {
opacity: 0;
}
.animated {
transition: opacity 1s;
}
.fadeIn {
opacity: 1;
}
一種更干凈的方法是為需要動畫的元素提供單個.animate
類:
<h1 class="h1 animate">STATISTICS</h1>
<p class="p1 animate">Lorem ipsum dolor sit amet... etc</p>
CSS用於.animate
和另一個.visible
類,如下所示:
.animate {
transition: opacity 1s;
opacity: 0;
}
.animate.visible {
opacity: 1;
}
然后,您可以使用JavaScript classList.add
方法切換可見性。
...
if (positionFromTop - windowHeight <= 0) {
elems[i].classList.add('visible');
} else {
elems[i].classList.remove('visible');
}
...
當您向上滾動時,這將淡出元素。
您還在每個滾動事件上調用checkPosition()
。 這可能會導致某些設備出現延遲,特別是如果checkPosition()
需要花費一些時間進行計算時。 有很多種方法可以解決此問題,包括在再次調用checkPosition()
之前checkPosition()
在指定時間段內等待的位置。 通過使用以下代碼替換添加滾動事件偵聽器的代碼,可以以100ms的等待時間進行反跳:
window.addEventListener( 'scroll', function() {
if ( !checkPosition.debounce ) {
checkPosition.debounce = setTimeout(function(){
delete checkPosition.debounce;
checkPosition();
}, 100);
}
} );
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