```js

<div id="root"></div>

<script>

import React from 'https://esm.sh/react@19';

import ReactDOM from 'https://esm.sh/react-dom@19/client';

const root = ReactDOM.createRoot(document.getElementById('root'));

root.render(<h1>Hello, world!</h1>);

</script>

```

---

HTML's hello world:

```html

<h1>Hello, world!</h1>

```

---

JS's hello world:

Nothing, it was already done in HTML

import { useState } from "react";

function Counter() { const [count, setCount] = useState(0);

  return (
    <button onClick={() => setCount(count + 1)}>
      Count: {count}
    </button>
  );

---------- Svelte:

<script> let count = 0; </script>

<button on:click={() => count += 1}> Count: {count} </button> --------------- React: function Editor({ initialText }) { const [text, setText] = useState(initialText);

  useEffect(() => {
    setText(initialText);
  }, [initialText]);

  return (
    <textarea
      value={text}
      onChange={e => setText(e.target.value)}
    />
  );

<script> export let initialText; let text = initialText;

  $: text = initialText;

<textarea bind:value={text} />