Switch

A remembered on/off boolean, driven by On / Off / Flip signals — the graph's toggle and one-bit memory.

Switch stores a single boolean state. The on (On), off (Off) and flip (Flip) signal inputs change it; onFromStart (State) is a boolean value input that sets the state directly and provides its initial value (default false). The current state is always readable on the state (Current State) boolean value output, and every state change also fires signals: switched (Switched) on any change, plus switchedToOn or switchedToOff matching the new state. on and off are ignored when the state already matches, so they never re-fire the signals; flip always changes state.

When to use it

The idiomatic node for anything a user toggles: expand/collapse, mute, edit mode. Use state (a level) to drive visible/enabled-style inputs, and the switched signals only when something must happen at the moment of change. For more than two states use States; for deriving a boolean from data rather than events, use Condition or Expression.

At a glance

Category	Logic
Type name	Switch
Available in	browser, cloud
SSR compatibility	safe
Provided by	noodl-runtime

Inputs

Values

Name	Type	Default	Description
onFromStart	Boolean	false	State to start in, and setting it announces a switch on Switched even though nothing switched

Signals

Name	Type	Default	Description
flip	Signal	—	Switches to whichever state it is not currently in
off	Signal	—	Switches off, or fires Unchanged if it is already off
on	Signal	—	Switches on, or fires Unchanged if it is already on

Outputs

Values

Name	Type	Default	Description
state	Boolean	—	True while the switch is on — wire it into a mounted or visible port for a gate that turns on AND off

Signals

Name	Type	Default	Description
completed	Signal	—	Fires after every invocation, whatever the outcome — wire this to carry on regardless. Failure still fires and still carries its reason, so this cannot hide an error
done	Signal	—	Fires when the switch actually changed state
switched	Signal	—	Fires on every state change, alongside whichever of Switched To On and Switched To Off applies
switchedToOff	Signal	—	Fires when the switch becomes off
switchedToOn	Signal	—	Fires when the switch becomes on
unchanged	Signal	—	Fires when it was already in that state, so none of the Switched signals fired

Patterns

• Button onClick → flip, state → a Group's visible: the standard show/hide toggle.
• state → Boolean To String input → the toggling button's label: the button describes what it will do next.

Watch out for

• Wiring switchedToOn (a momentary signal) to a boolean input like visible — it delivers only a pulse; use state for anything that must stay on.

Examples

Toggle a details panel with a self-labelling button

The standard show/hide toggle: one button flips a Switch, and everything else derives from the Switch's boolean state as levels — the details Group's visibility directly, the summary text's visibility through an Inverter (visible only while collapsed), and the button's own label through Boolean To String so the button always names what it will do next. Note the split of flow kinds: onClick → flip is a signal (momentary), while every state-derived wire is a value that holds its level.

Record audio in the browser and save it

The full arc of a MediaRecorder capture, which is longer than it looks because three different things have to be true before a single byte is recorded. A JavaScriptFunction asks for microphone permission and a Switch gates everything on the answer; a Javascript2 node owns the recorder itself and accumulates chunks; a second one runs the seconds counter; a third converts the finished Blob into the shape NewDbModelProperties can store. ⚠️ Permission is asynchronous and revocable, which is why the gate is a node and not an assumption — a recorder started before the user has answered produces silence rather than an error. The preview player is a Custom HTML node because an <audio> element with a blob URL is the shortest honest way to play back something that has no file yet.

Blink a button, and stop cleanly

A strobe is a good miniature of a hard problem: something that keeps running after the signal that started it, and therefore has to be stopped by something other than the thing that started it. A Javascript2 node owns the interval, a Switch turns it on and off, a States node carries the two appearances, and a Number makes the period an input instead of a literal. ⚠️ The half people leave out is the reset — stopping an interval without restoring the state leaves the button frozen in whichever half of the blink it happened to be in, which looks like a different bug entirely. This one restores it.

Related nodes

Condition, States, Inverter, Boolean To String, Value Changed

Generated

This page is generated from node-catalog-enriched.json. Do not edit it by hand — run npm run docs:nodes to regenerate, and fix the source enrichment instead.