Value Changed
Turns value changes into events: fires a signal every time its input receives a different value.
Value Changed watches one input of any type (value, displayed as Input) and fires the valueChanged (Value Changed) signal each time the incoming value differs from the last one it saw — including the very first value it receives. Comparison uses strict equality, so for objects and arrays a change means a different reference, not a mutation of the same object. It is the bridge from the value world (levels) to the signal world (events).
When to use it
Use it when something must happen at the moment data changes: restart a debounce Timer while the user types, re-run a Function when a selection changes, or trigger a save when a field updates. If you only need the value itself downstream, connect the value directly — no node needed. If you care about a boolean becoming true specifically, connect the boolean straight to a signal input (rising-edge trigger) instead.
At a glance
| Category | Logic |
| Type name | Value Changed |
| Available in | browser |
| SSR compatibility | safe |
| Provided by | noodl-viewer-react |
Inputs
Values
| Name | Type | Default | Description |
|---|---|---|---|
value | * | — | Value to watch; changes are detected by identity, so editing an Object or Array in place is not a change here |
Outputs
Signals
| Name | Type | Default | Description |
|---|---|---|---|
valueChanged | Signal | — | Fires when Input becomes a different value, including the first time it arrives |
Patterns
- A text input's
text→value,valueChanged→ a Timer'srestart: debounce — the Timer only finishes once typing pauses. valueChanged→ an Event Sender'ssendEvent: broadcast that a piece of state changed.
Watch out for
- Using it to detect a boolean turning true — it also fires on true→false. Connect the boolean directly to the target signal input (edge-triggered) or use Condition.
Examples
Debounced autosave with timestamped status
The debounce idiom: every keystroke fires Value Changed, whose signal restarts a 1.5-second Timer — the save only runs when the user pauses. The save Function stamps the moment; Date To String formats it, Unique Id issues a save id shortened by Substring, and String Format assembles the status line. Signals sequence the flow; values shape the display.
Related nodes
Condition, Switch, Delay, Expression
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