The src value of the source is indeed assigned successfully through jQuery. From the debugging point of view, the browser does not initiate a request to obtain the corresponding video, but simply assigns the value in the src of the a tag to the source.

But if you do this, the browser will request the address to get the video file:

$(".dj").on("click", function() {
   var src = $(this).data("src"),
       sourceDom = $("<source src=\""+ src +"\">");
       
   $("#video-box video").append(sourceDom);
   $("#video-box").show();
   
   // 自动播放
   $("#video-box video")[0].play()
});

Therefore, it can be inferred that when there is a source tag in the video, the browser will automatically obtain the address after rendering. Even if the address changes, the browser will not obtain the address again. However, by dynamically inserting the source tag, the browser can be triggered to reflow, thereby obtaining the file at the corresponding address for playback.

<video>
    <source src="xxx.mp4"/>
    <source src="xxx.ogg"/>
</video>

The src in source will only be checked once during rendering.
To dynamically adjust src, you should start with video. If you change it to this, it should be fine
$("#video-box video").prop(" src",src)

Don’t use the source tag, write it directly into the video tag; use attr() instead. Also, don’t write the width and height of the video tag in the style, take them out~

jsfidle cannot embed videos. Just change it to local

The video formats supported by the video tag include (1) H.264 encoded mp4 files (2) webm (3) ogg. Files with other suffixes are temporarily not supported due to patent issues and other issues. You can consider transcoding and try it

Just add a play() event