Array Changed

note

This node is not offered directly in the node picker.

Reports what changed inside an Array: items arriving and leaving with their index, and edits to the Objects within it.

Array Changed watches one Array and reports its changes as they happen. itemAdded (Item Added) and itemRemoved (Item Removed) fire per item with index (Index) and item (Item); itemChanged (Item Changed) fires when one of the Objects inside the Array is edited in place, with key (Key) naming the property that changed; arrayReplaced (Array Replaced) fires when a different Array arrives, including the first one. count (Count) always holds the current length. Every value port is written before its signal is sent. A wholesale replacement of an Array's contents is reported item by item, not as one opaque event, because the runtime emits the individual arrivals and departures. A pure reorder — sort, reverse, or writing length — sends no signal, because nothing was added or removed; Count is still kept accurate through it.

When to use it

Use it when a graph must react to what moved in an Array rather than that it changed — animating a row as it arrives, saving a record the moment a field inside it is edited, or keeping a running total. Value Changed is the right node when only the fact of a change matters: it compares identity, so an Array mutated in place is not a change there. Use Object Changed when the input is a single Object.

At a glance

Category	Logic
Type name	net.noodl.ArrayChanged
Available in	browser
SSR compatibility	safe
Provided by	noodl-viewer-react

Inputs

Values

Name	Type	Default	Description
array	Array	—	The Array to watch. Items arriving and leaving are reported as they happen, and edits to the Objects inside it are reported as Item Changed; sending a different Array reports Array Replaced

Outputs

Values

Name	Type	Default	Description
count	Number	—	How many items the watched Array holds now. Kept accurate through reordering and length changes, which send no signal because they add and remove nothing
index	Number	—	The position the last signal was about; empty after Array Replaced, which is about no single item
item	*	—	The item the last signal was about; empty after Array Replaced
key	String	—	The property of Item that changed, after Item Changed; empty after the other signals, which are about the item as a whole

Signals

Name	Type	Default	Description
arrayReplaced	Signal	—	Fires when a different Array arrives on the input, including the first one and including an explicit clear; Index, Item and Key are empty and Count is the new length
itemAdded	Signal	—	Fires when an item is added to the watched Array; Index and Item describe it
itemChanged	Signal	—	Fires when one of the Objects inside the watched Array is edited in place; Key names the property that changed. Items that are not Noodl Objects cannot be watched
itemRemoved	Signal	—	Fires when an item is removed from the watched Array; Index is the position it occupied

Patterns

• itemAdded → a Function's do with item wired in: run per-item work as rows arrive, without re-walking the whole Array.
• itemChanged with item and key → Set Record Properties: persist exactly the field an author edited.
• count → a Text node: a live item count that survives reordering.

Watch out for

• Expecting Item Changed for members that are not Noodl Objects. A plain object in the Array broadcasts nothing, so only its arrival and departure can be reported.
• Expecting a signal from sorting or reversing. Nothing was added or removed, so only Count is refreshed — watch the Array's own order downstream instead.
• Mutating a raw array with push and expecting a report. Use the Array node's own actions, or items, so the mutation goes through the reactive path.

Related nodes

Value Changed, Object Changed, Array, Repeater, Array Filter

Generated

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