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// Content was automatically extracted by Reffy into webref
// Source: CSS Font Loading Module Level 3 (
typedef (ArrayBuffer or ArrayBufferView) BinaryData;
dictionary FontFaceDescriptors {
CSSOMString style = "normal";
CSSOMString weight = "normal";
CSSOMString stretch = "normal";
CSSOMString unicodeRange = "U+0-10FFFF";
CSSOMString featureSettings = "normal";
CSSOMString variationSettings = "normal";
CSSOMString display = "auto";
CSSOMString ascentOverride = "normal";
CSSOMString descentOverride = "normal";
CSSOMString lineGapOverride = "normal";
enum FontFaceLoadStatus { "unloaded", "loading", "loaded", "error" };
interface FontFace {
constructor(CSSOMString family, (CSSOMString or BinaryData) source,
optional FontFaceDescriptors descriptors = {});
attribute CSSOMString family;
attribute CSSOMString style;
attribute CSSOMString weight;
attribute CSSOMString stretch;
attribute CSSOMString unicodeRange;
attribute CSSOMString featureSettings;
attribute CSSOMString variationSettings;
attribute CSSOMString display;
attribute CSSOMString ascentOverride;
attribute CSSOMString descentOverride;
attribute CSSOMString lineGapOverride;
readonly attribute FontFaceLoadStatus status;
Promise<FontFace> load();
readonly attribute Promise<FontFace> loaded;
interface FontFaceFeatures {
/* The CSSWG is still discussing what goes in here */
interface FontFaceVariationAxis {
readonly attribute DOMString name;
readonly attribute DOMString axisTag;
readonly attribute double minimumValue;
readonly attribute double maximumValue;
readonly attribute double defaultValue;
interface FontFaceVariations {
readonly setlike<FontFaceVariationAxis>;
interface FontFacePalette {
readonly attribute unsigned long length;
getter DOMString (unsigned long index);
readonly attribute boolean usableWithLightBackground;
readonly attribute boolean usableWithDarkBackground;
interface FontFacePalettes {
readonly attribute unsigned long length;
getter FontFacePalette (unsigned long index);
partial interface FontFace {
readonly attribute FontFaceFeatures features;
readonly attribute FontFaceVariations variations;
readonly attribute FontFacePalettes palettes;
dictionary FontFaceSetLoadEventInit : EventInit {
sequence<FontFace> fontfaces = [];
interface FontFaceSetLoadEvent : Event {
constructor(CSSOMString type, optional FontFaceSetLoadEventInit eventInitDict = {});
[SameObject] readonly attribute FrozenArray<FontFace> fontfaces;
enum FontFaceSetLoadStatus { "loading", "loaded" };
interface FontFaceSet : EventTarget {
constructor(sequence<FontFace> initialFaces);
FontFaceSet add(FontFace font);
boolean delete(FontFace font);
undefined clear();
// events for when loading state changes
attribute EventHandler onloading;
attribute EventHandler onloadingdone;
attribute EventHandler onloadingerror;
// check and start loads if appropriate
// and fulfill promise when all loads complete
Promise<sequence<FontFace>> load(CSSOMString font, optional CSSOMString text = " ");
// return whether all fonts in the fontlist are loaded
// (does not initiate load if not available)
boolean check(CSSOMString font, optional CSSOMString text = " ");
// async notification that font loading and layout operations are done
readonly attribute Promise<FontFaceSet> ready;
// loading state, "loading" while one or more fonts loading, "loaded" otherwise
readonly attribute FontFaceSetLoadStatus status;
interface mixin FontFaceSource {
readonly attribute FontFaceSet fonts;
Document includes FontFaceSource;
WorkerGlobalScope includes FontFaceSource;