在网页增加一个视频，视频 source 是一段 base64 字符串，它是一个 2.4kb 大小、16×16 像素、只有两帧黑色画面的视频，你可以把这段 base64 字符串转换为视频。
<video
id=”test-video”
muted
preload
loop
autoplay
playsinline
webkit-playsinline
>
<source
src=”data:video/mp4;base64,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”
/>
</video>
接着在这个页面增加一段 js 代码，用来判断这个视频是否自动播放，如果自动播放，则说明手机没有开启省电模式，如果没有自动播放，可以判断手机开启了省电模式：
const testVideo = document.getElementById(“test-video”);
testVideo.addEventListener(“canplaythrough”, (event) => {
if (testVideo.paused) {
window.lowPowerMode = true;
} else {
window.lowPowerMode = false;
}
testVideo.remove();
});
