Linking widgets

manywidgets are plain anywidgets, so they link like any anywidget — and they’re authored so those links also work in a static export with no kernel. There are two complementary tools.

1. jslink / jsdlink (canonical)¶

For a plain pass-through link — “when A’s trait changes, set B’s trait to the same value” — use ipywidgets’s browser-side links. They run entirely in the browser (no kernel round-trip), so they work both live and statically. The static-export plugin lifts these links into its host registry automatically.

from ipywidgets import jslink, jsdlink
from manywidgets import Chart, Slider

slider = Slider(label="Height", min=200, max=600, value=320)
chart = Chart(title="Linked chart", height=320)

# one-directional: slider.value -> chart.height
jsdlink((slider, "value"), (chart, "height"))

# bidirectional: jslink((a, "value"), (b, "value"))

• jsdlink(source, target) — one-directional.

• jslink(a, b) — bidirectional.

Use this whenever the two traits should hold the same value.

2. Binder (transforms & nested paths)¶

When the link needs a transform or has to write a nested / dotted-path target, jslink can’t express it. Binder covers those cases. It computes target = source * multiplier + offset and writes the result to the target field — including a dotted path like "view_state.zoom", which is merged into the parent dict.

from manywidgets import Binder, Chart, Slider

slider = Slider(label="Scale", min=1, max=10, value=3)
chart = Chart(title="Bound chart")

Binder(
    source=slider, source_field="value",
    target=chart, target_field="height",
    multiplier=100, offset=100,   # height = value*100 + 100
)

Binder accepts widget instances (it reads their widget_id) or explicit id strings. Traits: source_widget_id, source_field, target_widget_id, target_field, multiplier, offset, label.

Dotted-path targets¶

# write into a nested dict key (e.g. a lonboard map's view state)
Binder(source=zoom_slider, target=some_map, target_field="view_state.zoom")

The binder reads the current view_state, merges the new zoom, and writes the whole object back so listeners see a single coherent update.

Which one?¶

Both approaches work in a live kernel and in static export. Under the hood Binder resolves the other widgets through @manywidgets/core’s resolveModel, which handles the static-export hazards (a model id can map to several proxies; a widget’s wrapper may register late).