根据srcset
的文档,如果我们未在图片中指定sizes
,则浏览器将在渲染CSS后自动选择正确的图片。
<style>
img {
width: 400px;
}
</style>
<img
src="https://cdn.statically.io/img/wpspeedmatters.com/wp-content/uploads/2019/11/migrating-birds.jpg"
srcset="
https://cdn.statically.io/img/wpspeedmatters.com/wp-content/uploads/2019/11/migrating-birds.jpg?w=400 400w,
https://cdn.statically.io/img/wpspeedmatters.com/wp-content/uploads/2019/11/migrating-birds.jpg?w=700 700w,
https://cdn.statically.io/img/wpspeedmatters.com/wp-content/uploads/2019/11/migrating-birds.jpg?w=900 900w,
https://cdn.statically.io/img/wpspeedmatters.com/wp-content/uploads/2019/11/migrating-birds.jpg?w=1400 1400w,
https://cdn.statically.io/img/wpspeedmatters.com/wp-content/uploads/2019/11/migrating-birds.jpg?w=2000 2000w,
https://cdn.statically.io/img/wpspeedmatters.com/wp-content/uploads/2019/11/migrating-birds.jpg?w=3000 3000w
"
/>
在上面的示例中,图像在CSS中的大小调整为400px宽。 srcset
中给出了所有可能的大小。例如400px,700px,900px,1400px,2000px,3000px。
浏览器不会选择宽度为400px的图像,而是会选择2000px的图像。在手机上也是如此。