CSSPageDescriptors

The CSSPageDescriptors interface represents a CSS declaration block for an @page at-rule.

The interface exposes style information and various style-related methods and properties for the page. Each multi-word property has versions in camel- and snake-case. This means, for example, that you can access the margin-top CSS property using the syntax style["margin-top"] or style.marginTop (where style is a CSSPageDescriptor).

A CSSPageDescriptors object is accessed through the style property of the CSSPageRule interface, which can in turn be found using the CSSStyleSheet API.

This interface also inherits properties of its parent, CSSStyleDeclaration.

margin Experimental

A string representing the margin property of the corresponding @page at-rule.

margin-top Experimental

A string representing the margin-top property of the corresponding @page at-rule.

marginTop Experimental

A string representing the margin-top property of the corresponding @page at-rule.

margin-right Experimental

A string representing the margin-right property of the corresponding @page at-rule.

marginRight Experimental

A string representing the margin-right property of the corresponding @page at-rule.

margin-bottom Experimental

A string representing the margin-bottom property of the corresponding @page at-rule.

marginBottom Experimental

A string representing the margin-bottom property of the corresponding @page at-rule.

margin-left Experimental

A string representing the margin-left property of the corresponding @page at-rule.

marginLeft Experimental

A string representing the margin-left property of the corresponding @page at-rule.

size Experimental

A string representing the size property of the corresponding @page at-rule.

This interface inherits the methods of its parent, CSSStyleDeclaration.

This example gets the CSSPageDescriptors for a @page at-rule, if the object is supported on the browser, and then logs its properties.

CSS

Below we define styles for the page using a @page at-rule. We assign different values for each margin property using the margin shorthand, and also specify the size. We don't set the page-orientation. This allows us to see how the properties map in the Web API object.

@page {
  margin: 1cm 2px 3px 4px;
  /* page-orientation: upright; */
  size: A4;
}

JavaScript

First we check if CSSPageDescriptors is defined on the global window object, and if not we log that the interface is not supported.

If CSSPageDescriptors is supported, we get the document stylesheet at index 1, and then gets the cssRules defined in that stylesheet. We need to get this stylesheet because the example is embedded in a separate frame with its own sheet (index 0 is the CSS for this page).

We then iterate through the rules defined for the live example and match any that are of type CSSPageRule, as these correspond to @page rules. For the matching objects we then log the style and all its values.

if (typeof window.CSSPageDescriptors === "undefined") {
  log("CSSPageDescriptors is not supported on this browser.");
} else {
  // Get stylesheets for example and then get its cssRules
  const myRules = document.styleSheets[1].cssRules;
  for (let i = 0; i < myRules.length; i++) {
    if (myRules[i] instanceof CSSPageRule) {
      log(`${myRules[i].style}`);
      log(`margin: ${myRules[i].style.margin}`);

      // Access properties using CamelCase syntax
      log(`marginTop: ${myRules[i].style.marginTop}`);
      log(`marginRight: ${myRules[i].style.marginRight}`);
      log(`marginBottom: ${myRules[i].style.marginBottom}`);
      log(`marginLeft: ${myRules[i].style.marginLeft}`);
      log(`pageOrientation: ${myRules[i].style.pageOrientation}`);

      // Access properties using snake-case syntax
      log(`margin-top: ${myRules[i].style["margin-top"]}`);
      log(`margin-right: ${myRules[i].style["margin-right"]}`);
      log(`margin-left: ${myRules[i].style["margin-left"]}`);
      log(`margin-bottom: ${myRules[i].style["margin-bottom"]}`);
      log(`page-orientation: ${myRules[i].style["page-orientation"]}`);

      log(`size: ${myRules[i].style.size}`);

      // Log the original CSS text using inherited property: cssText
      log(`cssText: ${myRules[i].style.cssText}`);
      log("\n");
    }
  }
}

Results

The results are shown below. Note that the style object displayed at the top of the log should be a CSSPageDescriptors to match the current specification, but may be a CSSStyleDeclaration in some browsers. Note also that the corresponding values for properties in camel- and snake-case match each other and the @page declaration, and that page-orientation is the empty string "" because it is not defined in @page.