Question

所以我需要能够检查指定的id是否具有特定的类，但我不完全确定如何做到这一点。

这是我的代码。您可以看到我尝试在homeTransition函数中检查特定类的ID。

＆＃13;

function homeTransition()
    {   
        if(document.getElementById("aboutContent").hasClass("animated fadeInUp")){
            document.getElementById("aboutContent").className = " animated slideOutDown";
        } else if(document.getElementById("projectsContent").hasClass("animated fadeInUp")){
            document.getElementById("projectsContent").className = " animated slideOutDown";
            } else if(document.getElementById("contactContent").hasClass("animated fadeInUp")){
                document.getElementById("contactContent").className = " animated slideOutDown";
            }
                    document.getElementById("astronaut").className = " animated fadeIn";
    }

function aboutTransition()
    {   
        document.getElementById("astronaut").className = " animated fadeOut";
        document.getElementById("aboutContent").className = " animated fadeInUp";
        
        document.getElementById("projectsContent").className = " animated fadeOutLeft";
        document.getElementById("contactContent").className = " animated fadeOutLeft";
    }

function projectsTransition()
    {   
        document.getElementById("astronaut").className = " animated fadeOut";
        document.getElementById("projectsContent").className = " animated fadeInUp";
        
        document.getElementById("aboutContent").className = " animated fadeOutLeft";
        document.getElementById("contactContent").className = " animated fadeOutLeft";
    }

function contactTransition()
    {
        document.getElementById("astronaut").className = " animated fadeOut";
        document.getElementById("contactContent").className = " animated fadeInUp";
        
        document.getElementById("aboutContent").className = " animated fadeOutLeft";
        document.getElementById("projectsContent").className = " animated fadeOutLeft";
    }

//Menu
function expand(){
  $(this).toggleClass("on");
  $(".menu").toggleClass("active");
};
$(".button").on('click', expand);

＆＃13;

body {
  font-family: "Source Sans Pro", sans-serif;
  color: #ccc;
  z-index: -100;
  background-color: black;
  overflow: hidden;
}

#aboutContent {
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  padding: 0;
  overflow: hidden;
  width: 100%;
  height: 100%;
  transition: all 250ms;
  -webkit-transform: translateZ(0) translateX(-100%);
  transform: translateZ(0) translateX(-100%);
  background-color: #2b2b41;
  z-index: -1;
}

#projectsContent {
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  padding: 0;
  overflow: hidden;
  width: 100%;
  height: 100%;
  transition: all 250ms;
  -webkit-transform: translateZ(0) translateX(-100%);
  transform: translateZ(0) translateX(-100%);
  background-color: #42424b;
  z-index: -1;
}

#contactContent {
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  padding: 0;
  overflow: hidden;
  width: 100%;
  height: 100%;
  transition: all 250ms;
  -webkit-transform: translateZ(0) translateX(-100%);
  transform: translateZ(0) translateX(-100%);
  background-color: #353440;
  z-index: -1;
}

.menu {
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  padding: 0;
  overflow: hidden;
  background: rgba(45, 51, 54, 0.9);
  width: 18%;
  box-sizing: border-box;
  transition: all 250ms;
  -webkit-transform: translateZ(0) translateX(-100%);
  transform: translateZ(0) translateX(-100%);
  text-align:center;
  box-shadow: 0 0 20px #000000;
}

.active {
  transform: translateZ(0) translateX(0);
  transform: translateZ(0) translateX(0);
  -webkit-transition: 0.4s;
  transition: 0.4s;
  color: #e5e5e5;
}

h1 {
  margin-top:60%;
  font-size: 2.5em;
  cursor: default;
}

ul {
  padding:0;
  list-style:none;
  font-size:14px;
}

li {
  padding:10px 10px;
}

a {
  text-decoration:none;
  padding:10px 15px;
  color:#fff;
  font-family:"Roboto";
  font-size: 1.5em;
  font-weight: 300;
}

a:hover {
  text-decoration: line-through;
  color: #0dffec;
}

.content {
  position:relative;
  width:300px;
}

.button {
  width:20px;
  height:40px;
  margin:24% 36%;
  padding: 14px;
  cursor:pointer;
}

.line {
	width: 40px;
	height: 2px;
    background-color: #fff;
	transition: transform 0.3s ease, background 0.3s ease, opacity 0.3s ease, top 0.3s ease;
}

.line.first {
  transform: translateX(-10px) translateY(22px) rotate(-90deg);
}

.line.second {
  transform: translateX(-10px) translateY(19px) rotate(0deg);
}

.button.on .line.top {
	transform: translateX(-10px) translateY(20px) rotate(45deg);
}

.button.on .line.bottom {
	transform: translateX(-10px) translateY(17px)rotate(-45deg);
}

@keyframes fadein {
    from {
        opacity:0;
    }
    to {
        opacity:1;
    }
}
@-webkit-keyframes fadein { /* Safari and Chrome */
    from {
        opacity:0;
    }
    to {
        opacity:1;
    }
}

＆＃13;

<!DOCTYPE html>

<html>
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    
    <title>Home</title>
    
    <link href="https://fonts.googleapis.com/css?family=Source+Sans+Pro|Play|Raleway" rel="stylesheet">
    
    <link rel='stylesheet prefetch' href='http://maxcdn.bootstrapcdn.com/font-awesome/4.5.0/css/font-awesome.min.css'>
    
    <link rel="stylesheet" type="text/css" href="css/style.css">
    <link rel="stylesheet" type="text/css" href="css/animate.css">
</head> 
<body>
    
<div id="wrapper">
  <div class="menu">
      
    <h1>Title</h1>
      
    <ul>
       <div id="home" onclick="homeTransition()"><li><a href="#home"><i class="fa fa-home"></i> home</a></li></div>
       <div id="about" onclick="aboutTransition()"><li><a href="#about"><i class="fa fa-user"></i> about</a></li></div>
       <div id="projects" onclick="projectsTransition()"><li><a href="#projects"><i class="fa fa-code"></i> projects</a></li></div>
       <div id="contact" onclick="contactTransition()"><li><a href="#contact"><i class="fa fa-paper-plane"></i> contact</a></li></div>
    </ul>
  </div>
    
  <div class="content">
    <div class="button">
      <div class="line first top"></div>
      <div class="line second bottom"></div>
    </div>
  </div>
    
    
    
    <div id="aboutContent">
    
    </div>
    
    <div id="projectsContent">
    
    </div>
    
    <div id="contactContent">
    
    </div>
    
</div>
    
    <script src='http://cdnjs.cloudflare.com/ajax/libs/jquery/2.1.3/jquery.min.js'></script>
    <script src='http://cdnjs.cloudflare.com/ajax/libs/jqueryui/1.11.2/jquery-ui.min.js'></script>
    
    <script type="text/javascript" src="js/transition.js"></script>
    <script type="text/javascript" src="js/background.js"></script>
</body>
</html>

＆＃13;

Answer 1

你可以这样检查

document.getElementById("projectsContent").className.indexOf("animated") !== -1 // class exists on element

但是为此您只能检查一个类，如果要检查多个类将className存储在变量中并检查所有类或编写实用程序函数。

编辑：

正如@Jerinaw在评论中所提到的，你也可以使用下面的代码，如果你不需要支持＆lt; IE10

document.getElementById("projectsContent").classList.contains("animated") // class exists on element

Answer 2

使用vanilla Javascript

document.querySelector('#aboutContent.myclass');

这是：选择具有id（id选择器＃）aboutContent的元素，并且具有类（类选择器。）myClass。

阅读 CSS selectors
querySelector

我还想注意你似乎在混合使用vanilla javascript和jQuery。也许您应该阅读jQuery选择元素。

如何使用javascript检查特定的课程？

2 个答案: