1# Using Emitter for Inter-Thread Communication 2 3[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. 4 5 6To develop the Emitter mode, perform the following steps: 7 8 91. Subscribe to an event. 10 11 ```ts 12 import emitter from "@ohos.events.emitter"; 13 14 // Define an event with eventId 1. 15 let event = { 16 eventId: 1 17 }; 18 19 // Trigger the callback after the event with eventId 1 is received. 20 let callback = (eventData) => { 21 console.info('event callback'); 22 }; 23 24 // Subscribe to the event with eventId 1. 25 emitter.on(event, callback); 26 ``` 27 282. Emit the event. 29 30 ```ts 31 import emitter from "@ohos.events.emitter"; 32 33 // Define an event with eventId 1 and priority Low. 34 let event = { 35 eventId: 1, 36 priority: emitter.EventPriority.LOW 37 }; 38 39 let eventData = { 40 data: { 41 "content": "c", 42 "id": 1, 43 "isEmpty": false, 44 } 45 }; 46 47 // Emit the event with eventId 1 and event content eventData. 48 emitter.emit(event, eventData); 49 ``` 50