（1）JS修改HTML标签的属性：
<!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">
<title>js-dom-html</title>
</head>
<body>
<input type="text" id="input">
</body>
<script>
// JS将input标签的type属性修改成为button
document.getElementById('input').type = "button";
</script>
</html>(2) JS修改标签的样式：
<!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">
<title>js-dom-css</title>
<style>
#box{
height:100px;
width: 100px;
background-color: #000;
}
</style>
</head>
<body>
<div id="box"></div>
</body>
<script>
// JS 给 div 的样式增加个 边框的样式
document.getElementById('box').style.border = "1px solid #f00";
</script>
</html>