The HTMLVideoElement interface's read-only videoHeight property indicates the intrinsic height of the video, expressed in CSS pixels. In simple terms, this is the height of the media in its natural size.

An integer value specifying the intrinsic height of the video in CSS pixels. If the element's readyState is HTMLMediaElement.HAVE_NOTHING, then the value of this property is 0, because neither video nor poster frame size information is yet available.

A user agent calculates the intrinsic width and height of the element's media by starting with the media's raw pixel width and height, then taking into account factors including:

• The media's aspect ratio.
• The media's clean aperture (the sub-rectangle centered within the media that matches the target aspect ratio).
• The target device's resolution.
• Any other factors required by the media format.

If the element is currently displaying the poster frame rather than rendered video, the poster frame's intrinsic size is considered to be the size of the <video> element.

If at any time the intrinsic size of the media changes and the element's readyState isn't HAVE_NOTHING, a resize event will be sent to the <video> element. This can happen when the element switches from displaying the poster frame to displaying video content, or when the displayed video track changes.

This example creates a handler for the resize event that resizes the <video> element to match the intrinsic size of its contents.

let v = document.getElementById("myVideo");

v.addEventListener(
  "resize",
  (ev) => {
    let w = v.videoWidth;
    let h = v.videoHeight;

    if (w && h) {
      v.style.width = w;
      v.style.height = h;
    }
  },
  false,
);

Note that this only applies the change if both the videoWidth and the videoHeight are non-zero. This avoids applying invalid changes when there's no true information available yet for dimensions.