lovecoding
/
web0715


			
				
					
						
						
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							<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .active{
            color: red;
        }
    </style>
</head>
<body>
    <div class="box test">hello</div>
    <script>
        var oBox = document.getElementsByClassName("box")[0];

        oBox.onmouseenter = function(){
            // this.setAttribute("class","box active");
            // this.classList.add("active");
            // console.log(this.classList)
            // this.classList.remove("test");

            // this.classList.replace("test","active");
            
            // 获取类当中的所有值并且以字符串方式返回
            this.className = "box active";
            console.log(this.className)
        }
    </script>
</body>
</html>