代码很简单
scritp部分是这样：
<script>
var a =Math.random()*(4-1)+1;
document.getElementById("number").innerText = Math.floor(a);
</script>
body 部分是这样：
<body>
<div>
<span id="number"></span>
</div>
</body>
可结果老是这样：
我实在理解不了为什么
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和代码的加载顺序有关，放在头部获取的值是null，需要将script标签放在body里面
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<meta http-equiv="X-UA-Compatible" content="ie=edge,chrome=1" />
<meta name="renderer" content="webkit" />
<meta name="keywords" content="" />
<meta name="description" content="" />
<title>Document</title>
</head>
<body>
<div><span id="number">123</span></div>
<script>
document.getElementById('number').innerHTML = '新的内容';
</script>
</body>
</html>
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