과제1 let 제거하기

src/index.js

@@ -1,2 +1,47 @@
 /* eslint-disable react/react-in-jsx-scope, react/jsx-filename-extension */
 /* @jsx createElement */
+
+function createElement(tagName, props, ...children) {
+  const element = document.createElement(tagName);
+
+  Object.entries(props || {}).forEach(([key, value]) => {
+    element[key.toLowerCase()] = value;
+  });
+  children.flat().forEach((child) => {
+    if (child instanceof Node) {
+      element.appendChild(child);
+      return;
+    }
+    element.appendChild(document.createTextNode(child));
+  });
+
+  return element;
+}
+
+function render({ count }) {
+  function handleClick() {
+    render({
+      count: count + 1,
+    });
+  }
+
+  const element = (
+    <div>
+      <h1>과제 1</h1>
+      <p>
+        {[1, 2, 3, 4, 5, 6, 7, 8, 9].map((i) => (
+          <button type="button" onClick={() => handleClick()}>{i}</button>
+        ))}
+      </p>
+      <p>
+        {count}
+      </p>
+    </div>
+  );
+  document.getElementById('app').textContent = '';
+  document.getElementById('app').appendChild(element);
+}
+
+render({
+  count: 0,
+});