feat(schema): support blocking attributes (#489)

Author: harlan-zw

packages/unhead/src/types/schema/link.ts

@@ -1,6 +1,7 @@
 import type { HttpEventAttributes } from './attributes/event'
 import type { GlobalAttributes } from './attributes/global'
 import type { ReferrerPolicy } from './shared'
+import type { Blocking } from './struct/blocking'
 
 export type LinkRelTypes = 'alternate' |
   'author' |
@@ -33,7 +34,7 @@ export type LinkRelTypes = 'alternate' |
   'apple-touch-icon' |
   'apple-touch-startup-image'
 
-export interface LinkBase extends Pick<GlobalAttributes, 'nonce'> {
+export interface LinkBase extends Pick<GlobalAttributes, 'nonce'>, Blocking {
   /**
    * This attribute is only used when rel="preload" or rel="prefetch" has been set on the `<link>` element.
    * It specifies the type of content being loaded by the `<link>`, which is necessary for request matching,

packages/unhead/src/types/schema/script.ts

@@ -2,8 +2,9 @@ import type { Booleanable } from '../util'
 import type { HttpEventAttributes } from './attributes/event'
 import type { GlobalAttributes } from './attributes/global'
 import type { ReferrerPolicy } from './shared'
+import type { Blocking } from './struct/blocking'
 
-export interface ScriptBase extends Pick<GlobalAttributes, 'nonce'> {
+export interface ScriptBase extends Pick<GlobalAttributes, 'nonce'>, Blocking {
   /**
    * For classic scripts, if the async attribute is present,
    * then the classic script will be fetched in parallel to parsing and evaluated as soon as it is available.

packages/unhead/src/types/schema/struct/blocking.ts

@@ -0,0 +1,20 @@
+/**
+ * Represents the possible blocking tokens for an element.
+ */
+export type BlockingToken = 'render'
+
+/**
+ * Represents the blocking attribute for an element.
+ * The blocking attribute must have a value that is an unordered set of unique space-separated tokens,
+ * each of which are possible blocking tokens.
+ */
+export interface Blocking {
+  /**
+   * The blocking attribute indicates that certain operations should be blocked on the fetching of an external resource.
+   * The value is an unordered set of unique space-separated tokens, each of which are possible blocking tokens.
+   *
+   * @example
+   * blocking: "render"
+   */
+  blocking?: BlockingToken | string // escape hatch
+}

packages/unhead/src/types/schema/style.ts

@@ -1,4 +1,6 @@
-export interface Style {
+import type { Blocking } from './struct/blocking'
+
+export interface Style extends Blocking {
   /**
    * This attribute defines which media the style should be applied to.
    * Its value is a media query, which defaults to all if the attribute is missing.