我已经获得了预期的效果，但之后更新了HTML / CSS，JS又回到了zilch。
小提琴在这里 -
$( "#allies" ).hover(function() {
$('body').css("background", "url(https://s24.postimg.org/odj1bt6pf/allies_bg.jpg");
});
$( "#enemies" ).hover(function() {
$('body').css("background", "url(https://s24.postimg.org/rzouogd2r/enemies_bg.jpg");
});
$( "#fam" ).hover(function() {
$('body').css("background", "url(https://s29.postimg.org/46lataf5x/arch_neutral_cropped.png");
});/*css*/
#bg{
background-image:url('https://s29.postimg.org/46lataf5x/arch_neutral_cropped.png');
}
#wrap_main{display:block;
width:80%;
margin-left:auto;
margin-right:auto;
}
#fam{
display:block;
margin:auto;
border:double white 30pt;
width:100%-30pt;
float:center;
background-color: black;
font-family:fantasy, impact;
font-size:30pt;
text-align:center;
padding-bottom:2em;
}
#fam img{display:inline-block;
margin-left:auto;
margin-right:auto;
padding-top:10px;
padding-bottom:40px;
}
#fam a{text-decoration:none;
color:white;}
#fam a:hover{color:gold;}
#ae_seg{display:block;margin-left:auto;margin-right:auto;
}
#allies{
display:inline-block;
border:double 30pt;
background-color:white;
top:20%;
width:34%;
font-family:fantasy, impact;
font-size:30pt;
}
#allies ul li a{text-decoration:none;
color:black;}
#allies ul li a:hover{color:gold;}
#enemies{
display:inline-block;
border:double rgb(179,33,7) 30pt;
background-color:white;
float:right;
width:34%;
color:rgb(179,33,7);
font-family:fantasy, impact;
font-size:30pt;
}
#enemies ul li a{text-decoration:none;
color:black;}
#enemies ul li a:hover{color:gold;}
div img{
width:120px;
height:70px;
display:block;
margin-left:auto;
margin-right:auto;
padding-top:10px;
padding-bottom:5px;
}
#footer{
display:block;
margin:auto;
border:double white 30pt;
width:100%-30pt;
float:center;
background-color:rgb(179,33,7);
}
#footer img{height:120px;
}
#footer img:hover{
transform: rotate(-10deg);
}<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<body id="bg">
<div style="padding-bottom:10px;" id="fam">
<img style="display:block; margin-left:auto; margin-right:auto; pagging-top:10px;padding-bottom:40px;" src="http://fontmeme.com/permalink/170208/c2e98ece9088b3589606aa5f59e629f2.png">
<a href="https://apps.facebook.com/mobwars/family/index.php?family_id=79788" target="_blank">BBTG_VENG</a><span style="font-size:24pt;color:white;"> & BBTG tags</span>
</div>
<div id="wrap_main">
<div style="padding:4em;">
</div>
<div id="ae_seg">
<div id="allies">
<img src="http://fontmeme.com/permalink/170203/949c0c2c2c0c34c044b9b45585717a70.png">
<ul>
<li><a href="https://apps.facebook.com/mobwars/family/index.php?family_id=50978" target="_blank">ON HOLIDAY</a></li>
<li><a href="https://apps.facebook.com/mobwars/family/index.php?family_id=73574" target="_blank">AKD_FLGSHP</a><span style="font-size:24pt;"> & AKD tags</span></li>
<li><a href="https://apps.facebook.com/mobwars/family/index.php?family_id=77265" target="_blank">MOOzing</a><span style="font-size:24pt;"> & Cow related tags</span></li>
<li><a href="https://apps.facebook.com/mobwars/family/index.php?family_id=81836" target="_blank">S N G</a></li>
<li><a href="https://apps.facebook.com/mobwars/family/index.php?family_id=79535" target="_blank">CRIME CITY</a></li>
<li><a href="https://apps.facebook.com/mobwars/family/index.php?family_id=59564" target="_blank">BOUTIQUEOG</a></li>
<li><a href="https://apps.facebook.com/mobwars/family/index.php?family_id=80332" target="_blank">RKNHVK 1</a><span style="font-size:24pt;"> & RKN tags</span></li>
</ul>
</div>
<div id="enemies">
<img src="http://fontmeme.com/permalink/170203/e8d4db59e876e5c94bd8f072137e33e2.png">
<ul>
<li><a href="https://apps.facebook.com/mobwars/family/index.php?family_id=40" target="_blank">PHOENIX</a><span style="font-size:24pt;"> & PHX/PX tags</span></li>
<li><a href="https://apps.facebook.com/mobwars/family/index.php?family_id=42901" target="_blank">THEFALLEN</a></li>
<li><a href="https://apps.facebook.com/mobwars/family/index.php?family_id=79839" target="_blank">FALLENONES</a></li>
<li><a href="https://apps.facebook.com/mobwars/family/index.php?family_id=69048" target="_blank">CAULDRON</a></li>
<li><a href="https://apps.facebook.com/mobwars/family/index.php?family_id=81533" target="_blank">BC TA</a></li>
<li><a href="https://apps.facebook.com/mobwars/family/index.php?family_id=80207" target="_blank">DIMINISHED2</a></li>
<li><a href="https://apps.facebook.com/mobwars/family/index.php?family_id=81185" target="_blank">CLF WMD</a><span style="font-size:24pt;"> & WMD tags</span></li>
</ul>
</div>
</div>
<div style="padding:5.3em;">
</div>
</div>
<div style="padding-bottom:10px;" id="footer">
<a href="index.htm">
<img src="http://www.iconsdb.com/icons/preview/black/home-5-xxl.png">
</a>
</div>
</body>
</html>
我看不出它有什么问题，但那时我真的没那么有经验。
$( "#allies" ).hover(function() {
$('body').css("background", "url(https://s24.postimg.org/odj1bt6pf/allies_bg.jpg");
});
$( "#enemies" ).hover(function() {
$('body').css("background", "url(https://s24.postimg.org/rzouogd2r/enemies_bg.jpg");
});
$( "#fam" ).hover(function() {
$('body').css("background", "url(https://s29.postimg.org/46lataf5x/arch_neutral_cropped.png");
});
答案 0 :(得分：1)
现在正在使用，请在您的项目中添加jquery。
fiddle here
答案 1 :(得分：0)
其他人已在评论中解释过，您使用的是jQuery，而不是简单的JavaScript。 您需要将jQuery库附加到项目中。
<强> CDN 如果你想通过CDN使用jQuery，请使用以下代码：
<script src="https://code.jquery.com/jquery-3.1.1.min.js" integrity="sha256-hVVnYaiADRTO2PzUGmuLJr8BLUSjGIZsDYGmIJLv2b8=" crossorigin="anonymous"></script>
请参阅jQuery CDN
下载 如果你想在项目中使用自己的jQuery库副本，请下载here并按照以下方式实现：
<script src="jquery-3.1.1.min.js"></script>
请注意，如果您使用其他版本的jQuery，则需要更改此代码段中的版本号。