signalChange

Used to run an effect when a signal reference changes. For example can be useful for running an effect when an input signal changes to replace the ngOnChanges lifecycle hook. The effect function will be called with the current value of the signal and the previous value.

Presentation

function signalChange(
  signalRef: Signal<T> | InputSignal<T> | InputSignalWithTransform<T, unknown>,
  effectFn: (current: T, previous: T | undefined) => void,
  options?: { onCleanupFn?: (() => void) | undefined } | undefined,
): EffectRef;

Returns

EffectRef

Parameters

Name Type Description

Name	Type	Description
signalRef	`Signal<T> \| InputSignal<T> \| InputSignalWithTransform<T, unknown>`	@param signalRef The signal to be depend on
effectFn	`(current: T, previous: T \| undefined) => void`	@param effectFn The function to be called when the signal changes
options	`{ onCleanupFn?: (() => void) \| undefined; } \| undefined`	@param options Options for the effect onCleanupFn: A function to be called when the before on next effect run (not on the first run) and when the effect is destroyed

signalRef

Signal<T> | InputSignal<T> | InputSignalWithTransform<T, unknown>

@param signalRef The signal to be depend on

effectFn

(current: T, previous: T | undefined) => void

@param effectFn The function to be called when the signal changes

options

{ onCleanupFn?: (() => void) | undefined; } | undefined

@param options Options for the effect

onCleanupFn: A function to be called when the before on next effect run (not on the first run) and when the effect is destroyed

Example usage

myInputSignal = input('initial value');
signalChange(myInputSignal, (current, previous) => { console.log('myInputSignal changed', current, previous); });