检测浏览器是否支持webp
<script>
async function supportsWebp() {
if (!self.createImageBitmap) return false;
const webpData = 'data:image/webp;base64,UklGRh4AAABXRUJQVlA4TBEAAAAvAAAAAAfQ//73v/+BiOh/AAA=';
const blob = await fetch(webpData).then(r => r.blob());
return createImageBitmap(blob).then(() => true, () => false);
}
(async () => {
if (await supportsWebp()) {
const bg = document.getElementById('header');
bg.style.backgroundImage = "url(img/bg.webp)";
} else {
console.log('不支持');
}
})();
</script> 
