refactor(templating): attributes handling & JSX

- support unparented DOM nodes
- simpler attributes handling
- jsx-like syntax
- use .mjs for utils

examples/templating/index.js

@@ -1,3 +1,4 @@
+// @ts-check
 import { WebComponent, html } from "../../src/index.js";
 
 export class Counter extends WebComponent {
@@ -5,6 +6,19 @@ export class Counter extends WebComponent {
     count: 123,
   };
   get template() {
+
+    const list =  ['a', 'b', 'c', 'what']
+    const links = [
+      {
+        url: 'https://ayco.io',
+        text: 'Ayo Ayco'
+      },
+      {
+        url: 'https://ayco.io/gh/McFly',
+        text: 'McFly'
+      }
+    ]
+
     return html`
       <button
         class="hey"
@@ -21,6 +35,15 @@ export class Counter extends WebComponent {
         <label data-my-name="Ayo" for="the-input">Name</label>
         <input id="the-input" type="foo" value="Name:" />
       </form>
+      ${
+        list.map(item => html`<p>${item}</p>`)
+      }
+      <h3 about="Elephant">Links</h3>
+      <ul>
+        ${
+          links.map(link => html`<li><a href=${link.url} target="_blank">${link.text}</a></li>`)
+        }
+      </ul>
     `;
   }
 }

package.json

@@ -1,6 +1,6 @@
 {
   "name": "web-component-base",
-  "version": "2.0.0-beta.18",
+  "version": "2.0.0-beta.21",
   "description": "A zero-dependency, ~600 Bytes (minified & gzipped), JS base class for creating reactive custom elements easily",
   "type": "module",
   "exports": {

src/utils/create-element.js

@@ -1,42 +0,0 @@
-import { getCamelCase } from "./get-camel-case.js";
-
-export function createElement(tree) {
-  if (!tree.type) {
-    const leaves = typeof tree === "object" ? Object.keys(tree) : [];
-    if (leaves?.length > 1) {
-      return leaves.map((leaf) => createElement(tree[leaf]));
-    }
-    return document.createTextNode(tree);
-  } else {
-    const el = document.createElement(tree.type);
-    if (tree.props) {
-      Object.keys(tree.props).forEach((prop) => {
-        let domProp = prop.toLowerCase();
-        let value = tree.props[prop];
-        if (domProp.startsWith("data-")) {
-          const dataProp = domProp.replace("data-", "");
-          el.dataset[getCamelCase(dataProp)] = value;
-        } else if (domProp.startsWith("aria-")) {
-          el.setAttribute(domProp, value);
-        } else {
-          switch (domProp) {
-            case "class":
-              domProp = "className";
-              break;
-            case "for":
-              domProp = "htmlFor";
-              break;
-          }
-          if (domProp in el) el[domProp] = value;
-        }
-      });
-    }
-    tree.children?.forEach((child) => {
-      const childEl = createElement(child);
-      if (childEl) {
-        el.appendChild(childEl);
-      }
-    });
-    return el;
-  }
-}

src/utils/create-element.mjs

@@ -0,0 +1,29 @@
+export function createElement(tree) {
+  if (tree.type === undefined) {
+    if (Array.isArray(tree)) {
+      const frag = document.createDocumentFragment();
+      frag.replaceChildren(...tree.map(leaf => createElement(leaf)))
+      return frag;
+    }
+    return document.createTextNode(tree);
+  } else {
+    const el = document.createElement(tree.type);
+    if (tree.props) {
+      Object.keys(tree.props).forEach((prop) => {
+        const domProp = prop.toLowerCase();
+        if (domProp in el) {
+          el[domProp] = tree.props[prop];
+        } else {
+          el.setAttribute(prop, tree.props[prop])
+        }
+      });
+    }
+    tree.children?.forEach((child) => {
+      const childEl = createElement(child);
+      if (childEl instanceof Node) {
+        el.appendChild(childEl);
+      }
+    });
+    return el;
+  }
+}

src/utils/index.js

@@ -1,5 +1,5 @@
-export { serialize } from "./serialize.js";
-export { deserialize } from "./deserialize.js";
-export { getCamelCase } from "./get-camel-case.js";
-export { getKebabCase } from "./get-kebab-case.js";
-export {createElement} from "./create-element.js";
+export { serialize } from "./serialize.mjs";
+export { deserialize } from "./deserialize.mjs";
+export { getCamelCase } from "./get-camel-case.mjs";
+export { getKebabCase } from "./get-kebab-case.mjs";
+export {createElement} from "./create-element.mjs";

src/web-component-base.js

@@ -0,0 +1,200 @@
+import { createElement } from "./utils/create-element.mjs";
+import { getCamelCase } from "./utils/get-camel-case.mjs";
+import { getKebabCase } from "./utils/get-kebab-case.mjs";
+import { serialize } from "./utils/serialize.mjs";
+
+/**
+ * A minimal base class to reduce the complexity of creating reactive custom elements
+ * @license MIT <https://opensource.org/licenses/MIT>
+ * @author Ayo Ayco <https://ayo.ayco.io>
+ * @see https://www.npmjs.com/package/web-component-base#readme
+ */
+export class WebComponent extends HTMLElement {
+  /**
+   * Array of strings that tells the browsers which attributes will cause a render
+   * @type {Array<string>}
+   */
+  static properties = [];
+
+  /**
+   * Blueprint for the Proxy props
+   */
+  static props;
+
+  /**
+   * Read-only string property that represents how the component will be rendered
+   * @returns {string | Node | (string | Node)[]}
+   * @see https://www.npmjs.com/package/web-component-base#template-vs-render
+   */
+  get template() {
+    return "";
+  }
+
+  /**
+   * Read-only property containing camelCase counterparts of observed attributes.
+   * @typedef {{[name: string]: any}} PropStringMap
+   * @see https://www.npmjs.com/package/web-component-base#prop-access
+   * @see https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/dataset
+   * @type {PropStringMap}
+   */
+  get props() {
+    return this.#props;
+  }
+
+  /**
+   * @type {PropStringMap}
+   */
+  #props;
+
+  /**
+   * Triggered after view is initialized
+   */
+  afterViewInit() {}
+
+  /**
+   * Triggered when the component is connected to the DOM
+   */
+  onInit() {}
+
+  /**
+   * Triggered when the component is disconnected from the DOM
+   */
+  onDestroy() {}
+
+  /**
+   * Triggered when an attribute value changes
+   * @typedef {{
+   *  property: string,
+   *  previousValue: any,
+   *  currentValue: any
+   * }} Changes
+   * @param {Changes} changes
+   */
+  onChanges(changes) {}
+
+    constructor() {
+    super();
+    this.#initializeProps();
+  }
+
+  static get observedAttributes() {
+    const propKeys = this.props ? Object.keys(this.props).map(camelCase => getKebabCase(camelCase)) : [];
+
+    return [...(
+      new Set([
+        ...this.properties,
+        ...propKeys
+      ])
+    )]
+  }
+
+  connectedCallback() {
+    this.onInit();
+    this.render();
+    this.afterViewInit();
+  }
+
+  disconnectedCallback() {
+    this.onDestroy();
+  }
+
+  attributeChangedCallback(property, previousValue, currentValue) {
+    const camelCaps = getCamelCase(property);
+
+    if (previousValue !== currentValue) {
+      this[property] = currentValue === "" || currentValue;
+      this[camelCaps] = this[property];
+
+      this.#handleUpdateProp(camelCaps, this[property]);
+
+      this.render();
+      this.onChanges({ property, previousValue, currentValue });
+    }
+  }
+
+  #handleUpdateProp(key, stringifiedValue) {
+    const restored = deserialize(stringifiedValue, this.#typeMap[key]);
+    if (restored !== this.props[key]) this.props[key] = restored;
+  }
+
+  #typeMap = {};
+  #effectsMap = {};
+
+  #handler(setter, meta) {
+    const effectsMap = meta.#effectsMap;
+    const typeMap = meta.#typeMap;
+
+    return {
+      set(obj, prop, value) {
+        const oldValue = obj[prop];
+
+        if (!(prop in typeMap)) {
+          typeMap[prop] = typeof value;
+        }
+
+        if (value.attach === "effect") {
+          if (!effectsMap[prop]) {
+            effectsMap[prop] = [];
+          }
+          effectsMap[prop].push(value.callback);
+        } else if (typeMap[prop] !== typeof value) {
+            throw TypeError(`Cannot assign ${typeof value} to ${typeMap[prop]} property (setting '${prop}' of ${meta.constructor.name})`)
+        } else if (oldValue !== value) {
+          obj[prop] = value;
+          effectsMap[prop]?.forEach((f) => f(value));
+          const kebab = getKebabCase(prop);
+          setter(kebab, serialize(value));
+        }
+
+        return true;
+      },
+      get(obj, prop) {
+        // TODO: handle non-objects
+        if (obj[prop] !== null && obj[prop] !== undefined) {
+          Object.getPrototypeOf(obj[prop]).proxy = meta.#props;
+          Object.getPrototypeOf(obj[prop]).prop = prop;
+        }
+        return obj[prop];
+      },
+    };
+  }
+
+  #initializeProps() {
+    let initialProps = {}
+    if(this.constructor.props) {
+      initialProps = this.constructor.props;
+      Object.keys(initialProps).forEach(camelCase => {
+        const value = initialProps[camelCase]
+        this.#typeMap[camelCase] = typeof value
+        this.setAttribute(getKebabCase(camelCase), serialize(value))
+      })
+    }
+    if (!this.#props) {
+      this.#props = new Proxy(
+        initialProps,
+        this.#handler((key, value) => this.setAttribute(key, value), this)
+      );
+    }
+  }
+
+  #prevDOM;
+  render() {
+    if (typeof this.template === "string") {
+      this.innerHTML = this.template;
+      return;
+    } else if (typeof this.template === 'object') {
+      const tree = this.template;
+
+      // TODO: smart diffing
+      if (JSON.stringify(this.#prevDOM) !== JSON.stringify(tree)) {
+        // render
+        const el = createElement(tree);
+        if (el) {
+          if (Array.isArray(el)) this.replaceChildren(...el);
+          else this.replaceChildren(el);
+        }
+        this.#prevDOM = tree;
+      }
+    }
+  }
+}