RaspberryPiFoundation · gonfunko · Jun 11, 2025 · Jun 10, 2025 · Jun 11, 2025 · Jun 11, 2025
diff --git a/src/html_toast.ts b/src/html_toast.ts
@@ -0,0 +1,54 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import * as Blockly from 'blockly/core';
+
+/**
+ * Configuration options for toasts.
+ */
+interface HtmlToastOptions extends Blockly.ToastOptions {
+  element?: HTMLElement;
+}
+
+/**
+ * Custom toast implementation that supports HTML elements in toast messages.
+ *
+ * After registering, call 
+  `Blockly.dialog.toast(workspace, {element: <html element>, message: <text>});`
+ * to display an HTML-based toast.
+ */
+class HtmlToast extends Blockly.Toast {
+  /**
+   * Creates the body of the toast for display.
+   *
+   * @param workspace The workspace the toast will be displayed on.
+   * @param options Configuration options for toast appearance/behavior.
+   * @returns The body for the toast.
+   */
+  protected static override createDom(
+    workspace: Blockly.WorkspaceSvg,
+    options: HtmlToastOptions,
+  ) {
+    const dom = super.createDom(workspace, options);
+    const contents = dom.querySelector('div');
+    if (
+      contents &&
+      'element' in options &&
+      options.element instanceof HTMLElement
+    ) {
+      contents.innerHTML = '';
+      contents.appendChild(options.element);
+    }
+    return dom;
+  }
+}
+
+/**
+ * Registers HtmlToast as the default toast implementation for Blockly.
+ */
+export function registerHtmlToast() {
+  Blockly.dialog.setToast(HtmlToast.show.bind(HtmlToast));
+}
diff --git a/src/index.ts b/src/index.ts
@@ -7,6 +7,7 @@
 import * as Blockly from 'blockly/core';
 import {NavigationController} from './navigation_controller';
 import {enableBlocksOnDrag} from './disabled_blocks';
+import {registerHtmlToast} from './html_toast';
 
 /** Plugin for keyboard navigation. */
 export class KeyboardNavigation {
@@ -82,6 +83,8 @@ export class KeyboardNavigation {
     });
     workspace.getSvgGroup().appendChild(this.workspaceFocusRing);
     this.resizeWorkspaceRings();
+
+    registerHtmlToast();
   }
 
   private resizeWorkspaceRings() {

diff --git a/test/webdriverio/test/toast_test.ts b/test/webdriverio/test/toast_test.ts
@@ -0,0 +1,38 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import * as chai from 'chai';
+import * as Blockly from 'blockly/core';
+import {PAUSE_TIME, testFileLocations, testSetup} from './test_setup.js';
+
+suite('HTML toasts', function () {
+  setup(async function () {
+    this.browser = await testSetup(testFileLocations.BASE);
+    await this.browser.pause(PAUSE_TIME);
+  });
+
+  test('Can be displayed', async function () {
+    const equal = await this.browser.execute(() => {
+      const element = document.createElement('div');
+      element.id = 'testToast';
+      element.innerHTML = 'This is a <b>test</b>';
+
+      const options = {
+        element,
+        message: 'Placeholder',
+      };
+      Blockly.dialog.toast(
+        Blockly.getMainWorkspace() as Blockly.WorkspaceSvg,
+        options,
+      );
+
+      // Ensure that the element displayed in the toast is the one we specified.
+      return document.querySelector('.blocklyToast #testToast') === element;
+    });
+
+    chai.assert.isTrue(equal);
+  });
+});