Ecosyste.ms: Awesome
An open API service indexing awesome lists of open source software.
https://github.com/trambarhq/relaks-event-emitter
Event emitter for Relaks
https://github.com/trambarhq/relaks-event-emitter
Last synced: 2 days ago
JSON representation
Event emitter for Relaks
- Host: GitHub
- URL: https://github.com/trambarhq/relaks-event-emitter
- Owner: trambarhq
- License: mit
- Created: 2018-09-14T06:34:13.000Z (over 6 years ago)
- Default Branch: master
- Last Pushed: 2022-09-18T01:22:38.000Z (over 2 years ago)
- Last Synced: 2024-12-31T20:07:42.122Z (8 days ago)
- Language: JavaScript
- Homepage:
- Size: 230 KB
- Stars: 0
- Watchers: 3
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE
Awesome Lists containing this project
README
# Relaks Event Emitter
Relaks Event Emitter is the base class of data sources used by [Relaks](https://github.com/trambarhq/relaks) applications. It's designed for promised-based asynchronous code. It provides a notable feature allowing event listeners to postpone the default action associated with an event.
## Methods of emitter
* [addEventListener](#addeventlistener)
* [removeEventListener](#removeeventlistener)
* [triggerEvent](#triggerevent)
* [waitForEvent](#waitforevent)
### addEventListener
```typescript
function addEventListener(name: string, handler: function, beginning?:boolean): void
```
Add an event listener. If `beginning` is `true`, then `handler` will receive the event prior to handlers added previously. Otherwise it's placed at the end of the queue.
### removeEventListener
```typescript
function removeEventListener(name: string, handler: function): void
```
Remove an event listener.
### waitForEvent()
```typescript
async function waitForEvent(type: string): Event
```
Return a promise that is fulfilled when an event of the specified type occurs.
### triggerEvent
```typescript
function triggerEvent(evt: object): boolean
```
Send an event object to any listeners interested in the event. A method used by the event emitter itself. The return value indicates whether there were any listeners.
## Methods of event object
* [preventDefault](#preventdefault)
* [postponeDefault](#postponedefault)
* [stopImmediatePropagation](#stopimmediatepropagation)
* [waitForDecision](#waitfordecision)
### preventDefault
```typescript
function preventDefault(void): void
```
Indicate that the default action should not be performed.
### postponeDefault
```typescript
function postponeDefault(proceed: Promise): void
```
```typescript
function postponeDefault(callback: AsyncFunction): void
```
Request that the default action to be postponed. The method accepts either a promise or a callback function that returns a promise. An event emitter would wait for this promise to be fulfilled before perform the default action. If the promise's fulfillment value is `false` (and not merely "falsy"), that'd be the equivalent of calling `preventDefault()` and `stopImmediatePropagation()`--i.e. the default action will not occur.
When there are multiple listeners, a call to this method will keep other listeners from receiving the event until the promise given is fulfilled.
### stopImmediatePropagation
```typescript
function stopImmediatePropagation(void): void
```
Keep listeners further down the chain from receiving this event.
### waitForDecision
```typescript
async function waitForDecision(void): void
```
A method used by the event emitter itself. If a promise is given to `postponeDefault()` within an event handler, this method will wait for its fulfillment. The method returns immediately otherwise.