vscode-extension-samples/notebook-renderer-sample/src/client/render.ts

// We've set up this sample using CSS modules, which lets you import class
// names into JavaScript: https://github.com/css-modules/css-modules
// You can configure or change this in the webpack.config.js file.
import * as style from './style.css';
import type { RendererContext } from 'vscode-notebook-renderer';

interface IRenderInfo {
  container: HTMLElement;
  mime: string;
  value: any;
  context: RendererContext<unknown>;
}

// This function is called to render your contents.
export function render({ container, mime, value }: IRenderInfo) {
  // Format the JSON and insert it as <pre><code>{ ... }</code></pre>
  // Replace this with your custom code!
  const pre = document.createElement('pre');
  pre.classList.add(style.json);
  const code = document.createElement('code');
  code.textContent = `mime type: ${mime}\n\n${JSON.stringify(value, null, 2)}`;
  pre.appendChild(code);
  container.appendChild(pre);
}

if (module.hot) {
  module.hot.addDisposeHandler(() => {
    // In development, this will be called before the renderer is reloaded. You
    // can use this to clean up or stash any state.
  });
}