add allDefined util

docs/docs/usage.md

@@ -8,6 +8,30 @@ Web Awesome components are just regular HTML elements, or [custom elements](http
 
 If you're new to custom elements, often referred to as "web components," this section will familiarize you with how to use them.
 
+## Awaiting Registration
+
+Unlike traditional frameworks, custom elements don't have a centralized initialization phase. This means you need to verify that a custom element has been properly registered before attempting to interact with its properties or methods.
+
+You can use the [`customElements.whenDefined()`](https://developer.mozilla.org/en-US/docs/Web/API/CustomElementRegistry/whenDefined) method to ensure a specific component is ready:
+
+```ts
+await customElements.whenDefined('wa-button');
+
+// <wa-button> is ready to use!
+const button = document.querySelector('wa-button');
+```
+
+When working with multiple components, checking each one individually can become tedious. For convenience, Web Awesome provides the `allDefined()` function which automatically detects and waits for all Web Awesome components in the DOM to be initialized before resolving.
+
+```ts
+import { allDefined } from '/dist/webawesome.js';
+
+// Waits for all Web Awesome components in the DOM to be registered
+await allDefined();
+
+// All Web Awesome components on the page are ready!
+```
+
 ## Attributes & Properties
 
 Many components have properties that can be set using attributes. For example, buttons accept a `size` attribute that maps to the `size` property which dictates the button's size.

src/utilities/defined.ts

@@ -0,0 +1,64 @@
+interface AllDefinedOptions {
+  /**
+   * A callback that accepts a custom element tag name and returns `true` if the custom element should be defined before
+   * resolving or `false` to skip it. The tag name is always in lowercase.
+   */
+  match: (tagName: string) => boolean;
+
+  /**
+   * To wait for additional custom elements that may not be on the page when the function is called, provide them here.
+   */
+  additionalElements: string | string[];
+
+  /**
+   * The root in which to look for custom elements. Defaults to `document`. By design, shadow roots are not traversed,
+   * but you can call this function and set `root` to a custom element's shadow root if needed.
+   */
+  root: Document | ShadowRoot;
+}
+
+/**
+ * Waits for custom elements that are currently on the page to be registered before resolving. This is sugar for
+ * awaiting `customElements.whenDefined()` multiple times. By default, the function waits for all undefined Web Awesome
+ * elements, but you can pass a custom match function to wait for other custom elements instead.
+ *
+ * The function returns with `Promise.all()`, so any loading errors will cause it to reject. Make sure you handle errors
+ * accordingly using a try/catch block or a `.catch()`.
+ *
+ * @example
+ * // Wait for Web Awesome elements
+ * await allDefined();
+ *
+ * // Wait for all custom elements that start with `foo-` as well as the `<bar-button>` element
+ * await allDefined({
+ *   match: tagName => tagName.startsWith('foo-'),
+ *   additionalElements: ['bar-button', 'baz-dialog']
+ * });
+ */
+export async function allDefined(options?: Partial<AllDefinedOptions>) {
+  const opts: AllDefinedOptions = {
+    match: tagName => tagName.startsWith('wa-'),
+    additionalElements: [],
+    root: document,
+    ...options,
+  };
+
+  // Ensure additional elements is an array
+  const additionalElements = Array.isArray(opts.additionalElements)
+    ? opts.additionalElements
+    : [opts.additionalElements];
+
+  // Discover undefined elements in the document
+  const undefinedElements = [...opts.root.querySelectorAll(':not(:defined)')]
+    .map(el => el.localName)
+    .filter((tag, index, arr) => arr.indexOf(tag) === index) // make it unique
+    .filter(tag => opts.match(tag)); // make sure it matches
+
+  const tagsToAwait = [...undefinedElements, ...additionalElements];
+
+  // Wait for all to be registered
+  await Promise.all(tagsToAwait.map(tag => customElements.whenDefined(tag)));
+
+  // Wait a cycle for the first update
+  await new Promise(requestAnimationFrame);
+}

src/webawesome.ts

@@ -1,6 +1,7 @@
 export { registerIconLibrary, unregisterIconLibrary } from './components/icon/library.js';
 export { discover, preventTurboFouce, startLoader, stopLoader } from './utilities/autoloader.js';
 export { getBasePath, getKitCode, setBasePath, setKitCode } from './utilities/base-path.js';
+export { allDefined } from './utilities/defined.js';
 export { registerTranslation } from './utilities/localize.js';
 
 // Utilities