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Quickstart

pyobservablejs requires Python 3.11 or newer. Add it to an existing environment:

uv pip install pyobservablejs

Or open an isolated marimo editor with the package available:

uvx --with pyobservablejs marimo edit notebook.py

Create and render a notebook​

Paste this into a marimo cell or another anywidget notebook host:

import marimo as mo
import observablejs as obs

control = obs.ojs(
    """
    viewof threshold = Inputs.range([0, 1], {
      value: 0.5,
      step: 0.1,
      label: "Threshold"
    })
    """,
    key="threshold",
)

result = obs.js(
    'html`<strong>Threshold: ${threshold}</strong>`',
    key="result",
)

notebook = obs.Notebook(
    control,
    result,
    variables={"threshold": 0.5},
)

view = notebook.view()
widget = mo.ui.anywidget(view)
widget

Update the browser from Python​

Notebook.update_variables accepts one mapping. Every mounted view from this notebook receives the update.

notebook.update_variables({"threshold": 0.8})

Read a settled result​

NotebookView.state is one consistent, read-only snapshot. Read a result after the current input revision finishes.

widget.value  # rerun this cell when synchronized widget state changes
state = view.state

if (
    not state.pending
    and state.input_revision is not None
    and state.settled_revision == state.input_revision
):
    result_state = state.result("result")
    if result_state.status == "success":
        print(result_state.values)
    else:
        print(result_state.errors)

Continue with Core concepts, Build notebooks, Select cells, or Read results.