lovecoding
/
web250825


			
				
					
						
						
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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>
</head>
<body>
    <!-- 
        事件委托:
            减少内存消耗 避免多次循环
    -->
    <ul id="list">
        <li>1</li>
        <li>2</li>
        <li>3</li>
        <li>4</li>
    </ul>
    <button class="btn">添加</button>
    <script>
        var list = document.getElementById("list");
        var lists = document.querySelectorAll("#list li");
        var btn = document.getElementsByClassName("btn")[0];
        // console.log(btn)
        btn.onclick = function() {
           var li1 = document.createElement("li");
           console.log(li1)
           li1.innerText = Math.round(Math.random()*9+1);
           list.appendChild(li1);
        }
        list.onclick = function(event) {
            console.log(event)
            if(event.target.nodeName == 'LI') {
                console.log(event.target.innerText)
            }
        }
        // lists.onclick = function(event) {
        //     console.log(event,'121')
        // }
        // console.log(lists)
    </script>
</body>
</html>