---
name: anywidget-marimo
description: Toolkit for generating custom widgets from scratch for Marimo.
---

When writing an anywidget use vanilla javascript in `_esm` and do not forget about `_css`. The css should look bespoke in light mode and dark mode. Keep the css small unless explicitly asked to go the extra mile. When you display the widget it must be wrapped via `widget = mo.ui.anywidget(OriginalAnywidget())`.

<example title="Example anywidget implementation">
import anywidget
import traitlets


class CounterWidget(anywidget.AnyWidget):
    _esm = """
    // Define the main render function
    function render({ model, el }) {
      let count = () => model.get("number");
      let btn = document.createElement("button");
      btn.innerHTML = `count is ${count()}`;
      btn.addEventListener("click", () => {
        model.set("number", count() + 1);
        model.save_changes();
      });
      model.on("change:number", () => {
        btn.innerHTML = `count is ${count()}`;
      });
      el.appendChild(btn);
    }
    // Important! We must export at the bottom here!
    export default { render };
    """
    _css = """button{
      font-size: 14px;
    }"""
    number = traitlets.Int(0).tag(sync=True)

widget = mo.ui.anywidget(CounterWidget())
widget

# Grabbing the widget from another cell, `.value` is a dictionary.
print(widget.value["number"])
</example>

When sharing the anywidget, keep the example minimal. No need to combine it with marimo ui elements unless explicitly stated to do so.