<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<img id="light" src="imgs/off.gif"> <br>
<button onclick="lightFunction()" >点亮</button>
<!--
需求点亮电灯
1. img对象获取
2. 获取属性 src
3. 修改
4. 事件 (点击事件)
-->
<script>
function lightFunction(){
//img对象获取
let img = document.getElementById("light");
//获取属性 src 修改
img.src = "imgs/on.gif"
}
</script>
</body>
</html>