我是Javascript和Jquery的初學者。我試圖在滾動文字背景圖像發生變化的情況下實現效果。該代碼適用於從上到下滾動的正常工作,但一個圖像在從下往上滾動時不會更改。這是我的代碼,背景圖片在滾動時不會改變,但滾動時效果不錯
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<script>
$(window).scroll(function(){
var fromTopPx = 200; // distance to trigger
var scrolledFromtop = $(window).scrollTop();
if(scrolledFromtop > fromTopPx && scrolledFromtop < 600) // distance to trigger second background image
{
$('html').addClass('scrolled');
}
else if(scrolledFromtop > 600 && scrolledFromtop < 1000) // distance to trigger third background image
{
$('html').addClass('scrolledtwo');
}
else{
$('html').removeClass('scrolled');
$('html').removeClass('scrolledtwo')
}
});
</script>
<style>
html {
background-repeat: no-repeat;
background-position: center center;
background-attachment: fixed;
-webkit-background-size: cover;
-moz-background-size: cover;
-o-background-size: cover;
background-size: cover;
}
html {
background-image:url(assets/images/b1.jpeg);
}
html.scrolled {
background-image:url(assets/images/ab3.jpeg);
}
html.scrolledtwo {
background-image:url(assets/images/ab9.jpeg);
}
</style>
</head>
我在想什麼?
除去在其他類你如果和ELSEIF –