Class ConstraintListener

Listener for constraint lifecycle events.

Fires when a constraint matching the options filter wakes, sleeps, or breaks.

Valid events: CbEvent.WAKE, CbEvent.SLEEP, CbEvent.BREAK.

A BREAK event fires when the constraint exceeds its maxForce or maxError limit. If removeOnBreak is true on the constraint it is also removed from the space.

Example

const listener = new ConstraintListener(
  CbEvent.BREAK,
  myConstraintType,
  (cb) => { console.log(cb.constraint, 'broke!'); },
);
space.listeners.add(listener);

Fully modernized from nape-compiled.js lines 546–649.

Hierarchy (View Summary)

Listener
- ConstraintListener

Index

Constructors

constructor

new ConstraintListener(
    event: CbEvent,
    options: CbType | OptionType | null,
    handler: (cb: ConstraintCallback) => void,
    precedence?: number,
): ConstraintListener
Parameters
- event: CbEvent
  Must be CbEvent.WAKE, CbEvent.SLEEP, or CbEvent.BREAK.
- options: CbType | OptionType | null
  CbType or OptionType filter, or null to match all constraints.
- handler: (cb: ConstraintCallback) => void
  Called with a ConstraintCallback each time the event fires.
- precedence: number = 0
  Execution order relative to other listeners (higher = first). Default 0.
Returns ConstraintListener
Overrides Listener.constructor
- Defined in src/callbacks/ConstraintListener.ts:48

Accessors

event

get event(): CbEvent
The event this listener responds to.

Valid values depend on the concrete listener type — see CbEvent. Changing this while the listener is assigned to a space re-registers it.

Returns CbEvent
Inherited from Listener.event
- Defined in src/callbacks/Listener.ts:85
set event(event: CbEvent): void
Parameters
- event: CbEvent
Returns void
Inherited from Listener.event
- Defined in src/callbacks/Listener.ts:89

handler

get handler(): (cb: ConstraintCallback) => void
The callback function invoked when the event fires. Cannot be set to null.

Returns (cb: ConstraintCallback) => void
- Defined in src/callbacks/ConstraintListener.ts:101
set handler(handler: (cb: ConstraintCallback) => void): void
Parameters
- handler: (cb: ConstraintCallback) => void
Returns void
- Defined in src/callbacks/ConstraintListener.ts:105

options

get options(): OptionType
The filter used to match constraints. Returns an OptionType representing the current include/exclude configuration.

Returns OptionType
- Defined in src/callbacks/ConstraintListener.ts:92
set options(options: CbType | OptionType): void
Parameters
- options: CbType | OptionType
Returns void
- Defined in src/callbacks/ConstraintListener.ts:96

precedence

get precedence(): number
Execution priority of this listener relative to other listeners for the same event. Higher values execute first.

Returns number
Default Value
0
Inherited from Listener.precedence
- Defined in src/callbacks/Listener.ts:105
set precedence(precedence: number): void
Parameters
- precedence: number
Returns void
Inherited from Listener.precedence
- Defined in src/callbacks/Listener.ts:109

space

get space(): Space | null
The space this listener is currently registered in, or null if not registered.

Assign to register/unregister the listener in a space:
```
listener.space = mySpace;  // register
listener.space = null;     // unregister
```
Returns Space | null
Inherited from Listener.space
- Defined in src/callbacks/Listener.ts:125
set space(space: Space | null): void
Parameters
- space: Space | null
Returns void
Inherited from Listener.space
- Defined in src/callbacks/Listener.ts:133

type

get type(): ListenerType
The type of this listener (BODY, CONSTRAINT, INTERACTION, or PRE).

Returns ListenerType
Inherited from Listener.type
- Defined in src/callbacks/Listener.ts:75

Methods

toString

toString(): string
Returns string
Inherited from Listener.toString
- Defined in src/callbacks/Listener.ts:154

Class ConstraintListener

Example

Hierarchy (View Summary)

Index

Constructors

Accessors

Methods

Constructors

constructor

Parameters

Returns ConstraintListener

Accessors

event

Returns CbEvent

Parameters

Returns void

handler

Returns (cb: ConstraintCallback) => void

Parameters

Returns void

options

Returns OptionType

Parameters

Returns void

precedence

Returns number

Default Value

Parameters

Returns void

space

Returns Space | null

Parameters

Returns void

type

Returns ListenerType

Methods

toString

Returns string

Settings

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