How to handle object data inside html property in the Scheduler?

In React, the "html" property supports a string with HTML, but not JSX.

You can use JavaScript template literal (with backtick quotes) to insert variables into the HTML string. However, remember that the value isn't HTML-encoded in this case:

onBeforeEventRender: args => {
  const object = /* ... */ ;
  args.data.html = `<b>${object.name}</b>`;
}

You can also use JSX but you'll need to use onBeforeEventDomAdd event instead.

Please see the following tutorial for an example:
https://code.daypilot.org/50584/react-scheduler-rendering-jsx-in-events

It's also good to keep in mind that using JSX brings some overhead. It may be noticeable when there are many events in the current Scheduler viewport.