javascript - 加载时出现返回顶部按钮

Question

我希望我的“返回顶部链接”出现在滚动条上。目前，当我加载页面时，它会出现，当我尝试向下滚动时，它会闪烁一秒钟，然后再次出现。页面加载后，它可以完美运行。我想知道代码是否有错误。

<script type="text/javascript">
$('body').prepend('<a href="#" class="back-to-top">Back to Top</a>');
var amountScrolled = 200;
$(window).scroll(function() {
	if ( $(window).scrollTop() > amountScrolled ) {
		$('a.back-to-top').fadeIn('slow');
	} else {
		$('a.back-to-top').fadeOut('slow');
	}
});
$('a.back-to-top, a.simple-back-to-top').click(function() {
	$('html, body').animate({
		scrollTop: 0
	}, 700);
	return false;
});
</script>

a.back-to-top {
    background: #cccccc;
    bottom: 20px;
    color: #000000;
    height: 35px;
    padding: 5px 10px;
    position: fixed;
    right: 20px;
    width: 100px;
    z-index: 999;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.3.1/jquery.min.js"></script>
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Out too the been like hard off. Improve enquire welcome own beloved matters her. As insipidity so mr unsatiable increasing attachment motionless cultivated. Addition mr husbands unpacked occasion he oh. Is unsatiable if projecting boisterous insensible. It recommend be resolving pretended middleton. 

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Literature admiration frequently indulgence announcing are who you her. Was least quick after six. So it yourself repeated together cheerful. Neither it cordial so painful picture studied if. Sex him position doubtful resolved boy expenses. Her engrossed deficient northward and neglected favourite newspaper. But use peculiar produced concerns ten. 

An do on frankness so cordially immediate recommend contained. Imprudence insensible be literature unsatiable do. Of or imprudence solicitude affronting in mr possession. Compass journey he request on suppose limited of or. She margaret law thoughts proposal formerly. Speaking ladyship yet scarcely and mistaken end exertion dwelling. All decisively dispatched instrument particular way one devonshire. Applauded she sportsman explained for out objection. 

Enjoyed minutes related as at on on. Is fanny dried as often me. Goodness as reserved raptures to mistaken steepest oh screened he. Gravity he mr sixteen esteems. Mile home its new way with high told said. Finished no horrible blessing landlord dwelling dissuade if. Rent fond am he in on read. Anxious cordial demands settled entered in do to colonel. 

Now principles discovered off increasing how reasonably middletons men. Add seems out man met plate court sense. His joy she worth truth given. All year feet led view went sake. You agreeable breakfast his set perceived immediate. Stimulated man are projecting favourable middletons can cultivated. 

May musical arrival beloved luckily adapted him. Shyness mention married son she his started now. Rose if as past near were. To graceful he elegance oh moderate attended entrance pleasure. Vulgar saw fat sudden edward way played either. Thoughts smallest at or peculiar relation breeding produced an. At depart spirit on stairs. She the either are wisdom praise things she before. Be mother itself vanity favour do me of. Begin sex was power joy after had walls miles. 

Neat own nor she said see walk. And charm add green you these. Sang busy in this drew ye fine. At greater prepare musical so attacks as on distant. Improving age our her cordially intention. His devonshire sufficient precaution say preference middletons insipidity. Since might water hence the her worse. Concluded it offending dejection do earnestly as me direction. Nature played thirty all him. 

By impossible of in difficulty discovered celebrated ye. Justice joy manners boy met resolve produce. Bed head loud next plan rent had easy add him. As earnestly shameless elsewhere defective estimable fulfilled of. Esteem my advice it an excuse enable. Few household abilities believing determine zealously his repulsive. To open draw dear be by side like. 

</p>

Answer 1

首先给你的按钮一个display:none在你的CSS中。内联样式将覆盖您的样式表。

a.back-to-top {
  display:none
}

并更改prepend至append .

$('body').append('<a href="#" class="back-to-top">Back to Top</a>');

工作演示

$('body').append('<a href="#" class="back-to-top">Back to Top</a>');
var amountScrolled = 200;
$(window).scroll(function() {
	if ( $(window).scrollTop() > amountScrolled ) {
		$('a.back-to-top').fadeIn('slow');
	} else {
		$('a.back-to-top').fadeOut('slow');
	}
});
$('a.back-to-top, a.simple-back-to-top').click(function() {
	$('html, body').animate({
		scrollTop: 0
	}, 700);
	return false;
});

a.back-to-top {
    background: #cccccc;
    bottom: 20px;
    color: #000000;
    height: 35px;
    padding: 5px 10px;
    position: fixed;
    right: 20px;
    width: 100px;
    z-index: 999;
    display:none;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.3.1/jquery.min.js"></script>
<p>Style never met and those among great. At no or september sportsmen he perfectly happiness attending. Depending listening delivered off new she procuring satisfied sex existence. Person plenty answer to exeter it if. Law use assistance especially resolution cultivated did out sentiments unsatiable. Way necessary had intention happiness but september delighted his curiosity. Furniture furnished or on strangers neglected remainder engrossed. 

Out too the been like hard off. Improve enquire welcome own beloved matters her. As insipidity so mr unsatiable increasing attachment motionless cultivated. Addition mr husbands unpacked occasion he oh. Is unsatiable if projecting boisterous insensible. It recommend be resolving pretended middleton. 

It allowance prevailed enjoyment in it. Calling observe for who pressed raising his. Can connection instrument astonished unaffected his motionless preference. Announcing say boy precaution unaffected difficulty alteration him. Above be would at so going heard. Engaged at village at am equally proceed. Settle nay length almost ham direct extent. Agreement for listening remainder get attention law acuteness day. Now whatever surprise resolved elegance indulged own way outlived. 

Literature admiration frequently indulgence announcing are who you her. Was least quick after six. So it yourself repeated together cheerful. Neither it cordial so painful picture studied if. Sex him position doubtful resolved boy expenses. Her engrossed deficient northward and neglected favourite newspaper. But use peculiar produced concerns ten. 

An do on frankness so cordially immediate recommend contained. Imprudence insensible be literature unsatiable do. Of or imprudence solicitude affronting in mr possession. Compass journey he request on suppose limited of or. She margaret law thoughts proposal formerly. Speaking ladyship yet scarcely and mistaken end exertion dwelling. All decisively dispatched instrument particular way one devonshire. Applauded she sportsman explained for out objection. 

Enjoyed minutes related as at on on. Is fanny dried as often me. Goodness as reserved raptures to mistaken steepest oh screened he. Gravity he mr sixteen esteems. Mile home its new way with high told said. Finished no horrible blessing landlord dwelling dissuade if. Rent fond am he in on read. Anxious cordial demands settled entered in do to colonel. 

Now principles discovered off increasing how reasonably middletons men. Add seems out man met plate court sense. His joy she worth truth given. All year feet led view went sake. You agreeable breakfast his set perceived immediate. Stimulated man are projecting favourable middletons can cultivated. 

May musical arrival beloved luckily adapted him. Shyness mention married son she his started now. Rose if as past near were. To graceful he elegance oh moderate attended entrance pleasure. Vulgar saw fat sudden edward way played either. Thoughts smallest at or peculiar relation breeding produced an. At depart spirit on stairs. She the either are wisdom praise things she before. Be mother itself vanity favour do me of. Begin sex was power joy after had walls miles. 

Neat own nor she said see walk. And charm add green you these. Sang busy in this drew ye fine. At greater prepare musical so attacks as on distant. Improving age our her cordially intention. His devonshire sufficient precaution say preference middletons insipidity. Since might water hence the her worse. Concluded it offending dejection do earnestly as me direction. Nature played thirty all him. 

By impossible of in difficulty discovered celebrated ye. Justice joy manners boy met resolve produce. Bed head loud next plan rent had easy add him. As earnestly shameless elsewhere defective estimable fulfilled of. Esteem my advice it an excuse enable. Few household abilities believing determine zealously his repulsive. To open draw dear be by side like. 

</p>