Add support for :host pseudo-class

README.md

@@ -297,6 +297,8 @@ _As defined by CSS 4 and / or jQuery._
     - [`:scope`](https://developer.mozilla.org/en-US/docs/Web/CSS/:scope):
       Selects elements that are part of the scope of the current selector. This
       uses the context from the passed options.
+    - [`:host`](https://developer.mozilla.org/en-US/docs/Web/CSS/:host):
+      Alias of `:scope`, selecting elements in the current context.
 
 ---
 

src/pseudo-selectors/aliases.ts

@@ -11,6 +11,8 @@ const textControl =
  * Aliases are pseudos that are expressed as selectors.
  */
 export const aliases: Record<string, string> = {
+    host: ":scope",
+
     // Links
 
     "any-link": ":is(a, area, link)[href]",

test/pseudo-classes.ts

@@ -129,6 +129,26 @@ describe("unmatched", () => {
     });
 });
 
+describe(":host", () => {
+    it("should match the root element", () => {
+        const matches = CSSselect.selectAll(":host", dom);
+
+        expect(matches).toHaveLength(1);
+        expect(matches).toStrictEqual([dom[0]]);
+    });
+
+    it("should match context elements", () => {
+        const p = CSSselect.selectOne("p", dom);
+
+        expect(p).not.toBeNull();
+        expect(
+            CSSselect.selectAll(":host", dom, {
+                context: [p as Element],
+            }),
+        ).toStrictEqual([p]);
+    });
+});
+
 describe(":first-child", () => {
     it("should match", () => {
         const matches = CSSselect.selectAll(":first-child", dom);