2 files changed, 57 insertions, 0 deletions
diff --git a/op_crates/webidl/00_webidl.js b/op_crates/webidl/00_webidl.js
index 843fd329e..508abe44d 100644
--- a/op_crates/webidl/00_webidl.js
+++ b/op_crates/webidl/00_webidl.js
@@ -802,6 +802,50 @@
     throw new TypeError("Illegal constructor");
   }
 
+  function mixinPairIterable(name, prototype, dataSymbol, keyKey, valueKey) {
+    const methods = {
+      *entries() {
+        assertBranded(this, prototype);
+        for (const entry of this[dataSymbol]) {
+          yield [entry[keyKey], entry[valueKey]];
+        }
+      },
+      [Symbol.iterator]() {
+        assertBranded(this, prototype);
+        return this.entries();
+      },
+      *keys() {
+        assertBranded(this, prototype);
+        for (const entry of this[dataSymbol]) {
+          yield entry[keyKey];
+        }
+      },
+      *values() {
+        assertBranded(this, prototype);
+        for (const entry of this[dataSymbol]) {
+          yield entry[valueKey];
+        }
+      },
+      forEach(idlCallback, thisArg) {
+        assertBranded(this, prototype);
+        const prefix = `Failed to execute 'forEach' on '${name}'`;
+        requiredArguments(arguments.length, 1, { prefix });
+        idlCallback = converters["Function"](idlCallback, {
+          prefix,
+          context: "Argument 1",
+        });
+        idlCallback = idlCallback.bind(thisArg ?? globalThis);
+        const pairs = this[dataSymbol];
+        for (let i = 0; i < pairs.length; i++) {
+          const entry = pairs[i];
+          idlCallback(entry[valueKey], entry[keyKey], this);
+        }
+      },
+    };
+
+    return Object.assign(prototype.prototype, methods);
+  }
+
   window.__bootstrap ??= {};
   window.__bootstrap.webidl = {
     makeException,
@@ -817,5 +861,6 @@
     createBranded,
     assertBranded,
     illegalConstructor,
+    mixinPairIterable,
   };
 })(this);
diff --git a/op_crates/webidl/internal.d.ts b/op_crates/webidl/internal.d.ts
index 425ee674e..ca72566a5 100644
--- a/op_crates/webidl/internal.d.ts
+++ b/op_crates/webidl/internal.d.ts
@@ -286,6 +286,18 @@ declare namespace globalThis {
         v: Record<K, V>,
         opts: ValueConverterOpts,
       ) => any;
+
+      /**
+       * Mix in the iterable declarations defined in WebIDL.
+       * https://heycam.github.io/webidl/#es-iterable
+       */
+      declare function mixinPairIterable(
+        name: string,
+        prototype: any,
+        dataSymbol: symbol,
+        keyKey: string | number | symbol,
+        valueKey: string | number | symbol,
+      ): void;
     }
   }
 }