纯js实现录屏并保存视频到本地的尝试

本文介绍: js 实现录屏并保存视频到本地

const media = navigator.mediaDevices;

通过原型链可以查找到一些方法，如下图所示：通过打印如下：

其中 getDisplayMedi a 方法来获取用户的屏幕分享或屏幕捕获流，通常用于制作屏幕录像或视频会议等应用。

navigator.mediaDevices.getDisplayMedia({
  video: true,
});

在这段代码中，请求获取包含视频流的媒体许可，并将其存储在名为 stream 的变量中，以便后续使用。这个流可以用于在网页上显示屏幕共享或进行其他媒体处理操作。

又因为该方法是异步的，我们要编写如下代码：

&lt;body&gt;
  &lt;button&gt;共享屏幕</button&gt;
  <script&gt;
    const button = document.querySelector("button");
    button.addEventListener("click", async () => {
      const stream = await navigator.mediaDevices.getDisplayMedia({
        video: true,
      });
    });
  </script>
</body>

通过点击 button 按钮后会如下图所示效果：

const types = [
  "video/webm",
  "audio/webm",
  "video/webm;codecs=vp8",
  "video/webm;codecs=daala",
  "video/webm;codecs=h264",
  "audio/webm;codecs=opus",
  "video/mpeg",
];

const mime = MediaRecorder.isTypeSupported("video/webm;codecs=h264")
  ? "video/webm;codecs=h264"
  : "video/webm";

const mediaRecorder = new MediaRecorder(stream, { mimeType: mime });

const chunks = [];
mediaRecorder.addEventListener("dataavailable", function (e) {
  chunks.push(e.data);
});



mediaRecorder.addEventListener("stop", () => {
  const blob = new Blob(chunks, { type: chunks[0].type });
  const url = URL.createObjectURL(blob);
  const a = document.createElement("a");
  a.href = url;
  a.download = "video.webm";
  a.click();
});

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <button>共享屏幕</button>
    <script>
      const button = document.querySelector("button");
      button.addEventListener("click", async () => {
        const stream = await navigator.mediaDevices.getDisplayMedia({
          video: true,
        });

        const mime = MediaRecorder.isTypeSupported("video/webm;codecs=h264")
          ? "video/webm;codecs=h264"
          : "video/webm";

        const mediaRecorder = new MediaRecorder(stream, { mimeType: mime });

        const chunks = [];
        mediaRecorder.addEventListener("dataavailable", function (e) {
          chunks.push(e.data);
        });

        mediaRecorder.addEventListener("stop", () => {
          const blob = new Blob(chunks, { type: chunks[0].type });
          const url = URL.createObjectURL(blob);
          const a = document.createElement("a");
          a.href = url;
          a.download = "video.webm";
          a.click();
        });
        mediaRecorder.start();
      });
    </script>
  </body>
</html>

-const button = document.querySelector("button");
-button.addEventListener("click", async () => {
    ...
})

+const body = document.body;
+body.addEventListener("click", async () => {
    ....
})

	const body = document.body;
	body.addEventListener("click", async () => {
        const stream = await navigator.mediaDevices.getDisplayMedia({
          video: true,
        });
        const mime = MediaRecorder.isTypeSupported("video/webm;codecs=h264")
          ? "video/webm;codecs=h264"
          : "video/webm";

        const mediaRecorder = new MediaRecorder(stream, { mimeType: mime });

        const chunks = [];
        mediaRecorder.addEventListener("dataavailable", function (e) {
          chunks.push(e.data);
        });

        mediaRecorder.addEventListener("stop", () => {
          const blob = new Blob(chunks, { type: chunks[0].type });
          const url = URL.createObjectURL(blob);
          const a = document.createElement("a");
          a.href = url;
          a.download = "video.mp4";
          a.click();
        });
        mediaRecorder.start();
      });