Document: mozSetImageElement() method

Non-standard: This feature is not standardized. We do not recommend using non-standard features in production, as they have limited browser support, and may change or be removed. However, they can be a suitable alternative in specific cases where no standard option exists.

The Document.mozSetImageElement() method changes the element being used as the CSS background for a background with a given background element ID.

Syntax

mozSetImageElement(imageElementId, imageElement)

Parameters

imageElementId: A string indicating the name of an element that has been specified as a background image using the -moz-element CSS function.
imageElement: The new element to use as the background corresponding to that image element string. Specify null to remove the background element.

Return value

None (undefined).

Examples

This example changes the background of a <div> block each time the block is clicked by the user.

View this example live.

html

<style>
  #my-box {
    background-image: -moz-element(#canvas-bg);
    text-align: center;
    width: 400px;
    height: 400px;
    cursor: pointer;
  }
</style>

The CSS defined by the <style> block above is used by our <div> to use an element with the id "canvas-bg" as its background.

let c = 0x00;
function clicked() {
  const canvas = document.createElement("canvas");
  canvas.setAttribute("width", 100);
  canvas.setAttribute("height", 100);

  const ctx = canvas.getContext("2d");
  ctx.fillStyle = `#${c.toString(16)}0000`;
  ctx.fillRect(25, 25, 75, 75);

  c += 0x11;
  if (c > 0xff) {
    c = 0x00;
  }

  document.mozSetImageElement("canvas-bg", canvas);
}

The code here is called each time the user clicks the <div> element. It creates a new <canvas> with the width and height set to 100 pixels, then draws into it a 50 by 50 pixel square. Each time the function is called, the square is a different color (its red component is increased each time), so each time the user clicks the element, the background is filled with a brighter and brighter pattern of red tiles.

Once the canvas is drawn, document.mozSetImageElement() is called to set the background for any CSS using the ID "canvas-bg" as its background element ID to be our new canvas.

Specifications

Not part of any specification.