html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>JS-对象-DOM-案例</title>
</head>
<body>
<img id="h1" src="img/off.gif"> <br><br>
<div class="cls">传智教育</div> <br>
<div class="cls">黑马程序员</div> <br>
<input type="checkbox" name="hobby"> 电影
<input type="checkbox" name="hobby"> 旅游
<input type="checkbox" name="hobby"> 游戏
</body>
<script>
//1. 点亮灯泡 : src 属性值
var img=document.getElementById('h1');
img.src="img/on.gif";
//2. 将所有div标签的内容后面加上: very good (红色字体) -- <font color='red'></font>
var divs=document.getElementsByTagName('div');
for (let i = 0; i < divs.length; i++) {
const divsi = divs[i];
divsi.innerHTML+="<font color='red'>very godd<font>";
}
//3. 使所有的复选框呈现选中状态
var hobbys=document.getElementsByName('hobby');
for (let i = 0; i < hobbys.length; i++) {
const hobby = hobbys[i];
hobby.checked=true;
}
</script>
</html>