下面的两种解决办法都会导致图片缩小，可以给图片进行初始化的宽高设置
<!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>Document</title>
<style>
html,body {
margin: 0;
padding: 0;
}
#box {
box-sizing: border-box;
width: 100%;
height: 240px;
background: pink;
}
#image {
transform: rotate(0);
object-fit: contain;
}
#btn {
margin-top: 100px;
}
</style>
</head>
<body>
<div id="box">
<img id="image" src="https://www.runoob.com/images/pulpit.jpg" alt="">
<!-- <img id="image" src="https://pics0.baidu.com/feed/c2cec3fdfc039245259830d9727ca5c77c1e2521.jpeg@f_auto?token=b910f4287521294b9469788c77a3ac93&s=A12326BEC5137FDECCBC8DC1030060BB" alt=""> -->
</div>
<button id="btn">旋转</button>
</body>
<script>
window.onload = () => {
let btn = document.getElementById('btn')
let image = document.getElementById('image')
let box = document.getElementById('box')
let childRawWidth = image.offsetWidth // 原始的图片宽
let childRawHeight = image.offsetHeight // 原始的图片高
let deg = 0
btn.onclick = function() {
if (deg > 360) {
deg = 0
} else {
deg += 90
}
// 方法一：使用 scale -- 父元素的高度不固定
// let childWidth = image.offsetWidth
// let childHeight = image.offsetHeight
// let scalePix = 1
// if (childWidth > childHeight) {
// scalePix = childHeight / childWidth
// } else {
// scalePix = childWidth / childHeight
// }
// image.style.transform = `rotate(${deg}deg) scale(${scalePix}, 1)`
// 方法二：将图片重新设置宽高 -- 父元素的高度固定
let parentWidth = box.offsetWidth
let parentHeight = box.offsetHeight
if (childRawWidth > childRawHeight) {
image.style.width = childRawHeight + 'px'
}
image.style.transform = `rotate(${
deg}deg)`
}
}
</script>
</html>
原始图片：
超出的效果图：
解决之后的效果图：
