1# Using Emitter for Inter-Thread Communication 2 3 4[Emitter](../reference/apis/js-apis-emitter.md) provides APIs for sending and processing events between threads, including the APIs for processing events that are subscribed to in persistent or one-shot manner, unsubscribing from events, and emitting events to the event queue. 5 6 7To develop the Emitter mode, perform the following steps: 8 9 101. Subscribe to an event. 11 12 ```ts 13 import emitter from "@ohos.events.emitter"; 14 15 // Define an event with eventId 1. 16 let event = { 17 eventId: 1 18 }; 19 20 // Trigger the callback after the event with eventId 1 is received. 21 let callback = (eventData) => { 22 console.info('event callback'); 23 }; 24 25 // Subscribe to the event with eventId 1. 26 emitter.on(event, callback); 27 ``` 28 292. Emit the event. 30 31 ```ts 32 import emitter from "@ohos.events.emitter"; 33 34 // Define an event with eventId 1 and priority Low. 35 let event = { 36 eventId: 1, 37 priority: emitter.EventPriority.LOW 38 }; 39 40 let eventData = { 41 data: { 42 "content": "c", 43 "id": 1, 44 "isEmpty": false, 45 } 46 }; 47 48 // Emit the event with eventId 1 and event content eventData. 49 emitter.emit(event, eventData); 50 ``` 51