我自己写的案例
<!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">
<link rel="stylesheet" href="./css/index.css">
<title>Document</title>
<style>
#box{
width: 100px;
height: 100px;
background-color: red;
margin: 20px 80px;
}
</style>
</head>
<body>
<div id="box"></div>
<input type="button" value="变高" onclick="aa()">
<input type="button" value="变宽" onclick="bb()">
<input type="button" value="变色" onclick="cc()">
<input type="button" value="重置" onclick="dd()">
<input type="button" value="隐藏" onclick="ee()">
<input type="button" value="显示" onclick="ff()">
<script>
let box
window.onload = function(){
box = document.getElementById("box");
}
function aa() {
box.style.height = "400px"
}
function bb() {
box.style.width = "400px"
}
function bb() {
box.style.width = "400px"
}
function cc() {
box.style.background = "pink"
}
function dd() {
box.style.height = "100px"
box.style.width = "100px"
box.style.background = "red"
}
function ee() {
box.style.display = "none"
}
function ff() {
box.style.display = "block"
}
</script>
</body>
<script src="./js/index.js"></script>
</html>