https://github.com/themost-framework/events

Sync and async event emitters
https://github.com/themost-framework/events

async emitter emitting event event-driven events subscribe subscription sync

Last synced: about 7 hours ago
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Sync and async event emitters

• Host: GitHub
• URL: https://github.com/themost-framework/events
• Owner: themost-framework
• License: bsd-3-clause
• Created: 2022-09-15T03:50:21.000Z (about 2 years ago)
• Default Branch: main
• Last Pushed: 2023-08-31T08:39:53.000Z (about 1 year ago)
• Last Synced: 2024-11-06T16:00:41.397Z (10 days ago)
• Topics: async, emitter, emitting, event, event-driven, events, subscribe, subscription, sync
• Language: TypeScript
• Homepage:
• Size: 191 KB
• Stars: 1
• Watchers: 2
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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# @themost/events

Sync and async event emitters for both browser and node.js

## Usage

    npm i @themost/events

### AsyncSeriesEventEmitter

Use `AsyncSeriesEventEmitter` for executing a collection of async event subscribers in series. 

The following example demonstrates a before load event which executes event subscribers and continues.

    const { AsyncSeriesEventEmitter } = require('@themost/events');

    class UserAction {

        

        constructor() {

            this.beforeLoad = new AsyncSeriesEventEmitter();

        }

        

        async load() {

            await this.beforeLoad.emit({

                target: this

            });

            this.dateCreated = new Date();

        }        

    }

    (async function () {

        const item = new UserAction();

        item.beforeLoad.subscribe((event) => {

            event.target.status = 'waiting';

        });

    

        item.beforeLoad.subscribe((event) => {

            return new Promise((resolve) => {

                // wait for something

                setTimeout(() => {

                    event.target.status = 'active';

                    resolve();

                }, 1000);

            });

        });

        await item.load();

        console.log('Loaded', 'status', item.status);

    })().then(() => {

        //

    });

### AsyncEventEmitter

Use `AsyncEventEmitter` for executing a collection of async event subscribers in parallel.

    const { AsyncEventEmitter } = require('@themost/events');

    class UserAction {

        

        constructor() {

            this.beforeLoad = new AsyncEventEmitter();

        }

        

        async load() {

            this.beforeLoad.emit({

                target: this

            });

            this.dateCreated = new Date();

        }        

    }

    const item = new UserAction();

    item.beforeLoad.subscribe((event) => {

        event.target.status = 'waiting';

    });

    item.beforeLoad.subscribe((event) => {

        return new Promise((resolve) => {

            // wait for something

            setTimeout(() => {

                event.target.status = 'active';

                resolve();

            }, 1000);

        });

    });

    item.load();

### SyncSeriesEventEmitter

Use `SyncSeriesEventEmitter` for executing a collection of sync event subscribers in series.

The following example demonstrates an after load event which executes event subscribers and continues.

    const { SyncSeriesEventEmitter } = require('@themost/events');

    class UserAction {

        constructor() {

            this.afterLoad = new SyncSeriesEventEmitter();

        }

        

        load() {

            this.status = 'unknown';

            this.afterLoad.emit({

                target: this

            });

        }        

    }

    const item = new UserAction();

    item.afterLoad.subscribe((event) => {

        event.target.status = 'waiting';

        event.target.dateCreated = new Date();

    });

    item.afterLoad.subscribe((event) => {

        if (event.target.status === 'waiting') {

            event.target.status = 'active';

        }

    });

    

    // perform load

    item.load();

    console.log('Loaded', 'status', item.status);

    console.log('Loaded', 'dateCreated', item.dateCreated);

### ProcessEventEmitter

Use `ProcessEventEmitter` for sending and receiving process messages in both fork and cluster mode under node.js.

Import `@themost/events/platform-server/register` in your startup script

    import '@themost/events/platform-server/register'

If your application is running in cluster mode, each message received by the primary process will be forwarded to each worker of a cluster. This operation is very important when you are implementing shared services across cluster workers and enables the communication between of them.

Start sending and receiving messages:

    new ProcessEventEmitter().emit(msg);

    ...

    new ProcessEventEmitter().subscribe((value) => {

        // write your code here

    });