Add a type for TranscriptEvent

Readme.md

@@ -12,7 +12,7 @@ With YARN install the module with: `yarn add aws-transcribe`
 An example of streaming from microphone can be found in src/examples/stream-from-microphone.ts
 
 ```typescript
-import { AwsTranscribe, StreamingClient } from "aws-transcribe"
+import { AwsTranscribe, StreamingClient, TranscriptEvent } from "aws-transcribe"
 
 const client = new AwsTranscribe({
     // if these aren't provided, they will be taken from the environment
@@ -30,7 +30,7 @@ const transcribeStream = client
     .on(StreamingClient.EVENTS.OPEN, () => console.log(`transcribe connection opened`))
     .on(StreamingClient.EVENTS.ERROR, console.error)
     .on(StreamingClient.EVENTS.CLOSE, () => console.log(`transcribe connection closed`))
-    .on(StreamingClient.EVENTS.DATA, (data) => {
+    .on(StreamingClient.EVENTS.DATA, (data: TranscriptEvent) => {
         const results = data.Transcript.Results
 
         if (!results || results.length === 0) {

src/StreamingClient.ts

@@ -4,6 +4,7 @@ import { Writable } from "stream"
 import { createDebugger } from "./utils"
 import { TranscribeException } from "./TranscribeException"
 import { fromBinary, toBinary } from "./aws-message-utils"
+import { TranscriptEvent } from ".";
 
 const debugLog = createDebugger(__filename)
 
@@ -63,7 +64,7 @@ export class StreamingClient extends Writable {
         if (wrapper.headers[":message-type"].value === "event") {
             const eventType = wrapper.headers[":event-type"].value
             debugLog(`${eventType}: `, body)
-            this.emit(StreamingClient.EVENTS.DATA, body, eventType)
+            this.emit(StreamingClient.EVENTS.DATA, body as TranscriptEvent, eventType)
         } else {
             // message type is exception
             // exception type is supposed to be one from EXCEPTIONS

src/__tests__/StreamingClient.test.ts

@@ -1,7 +1,7 @@
 jest.mock("ws")
 
 import WsServer from "jest-websocket-mock"
-import { StreamingClient } from "../index"
+import { StreamingClient, TranscriptEvent } from "../index"
 import { TranscribeException } from "../TranscribeException"
 import {
     getBinaryEvent,
@@ -80,7 +80,7 @@ describe("StreamingClient", () => {
                     const body = createBodyForTranscriptionEvent(`a random transcription`, false)
                     const event = "TranscriptionEvent"
                     const message = getBinaryEvent(event, body)
-                    client.on(StreamingClient.EVENTS.DATA, (data, eventName) => {
+                    client.on(StreamingClient.EVENTS.DATA, (data: TranscriptEvent, eventName: string) => {
                         expect(data).toEqual(body)
                         expect(eventName).toBe(event)
                         done()

src/examples/stream-from-microphone.ts

@@ -1,4 +1,4 @@
-import { AwsTranscribe, StreamingClient } from "../index"
+import { AwsTranscribe, StreamingClient, TranscriptEvent } from "../index"
 
 // eslint-disable-next-line @typescript-eslint/no-var-requires
 const recorder = require("node-record-lpcm16")
@@ -41,7 +41,7 @@ const transcribeStream = client
     .on(StreamingClient.EVENTS.OPEN, () => console.log(`transcribe connection opened`))
     .on(StreamingClient.EVENTS.ERROR, console.error)
     .on(StreamingClient.EVENTS.CLOSE, () => console.log(`transcribe connection closed`))
-    .on(StreamingClient.EVENTS.DATA, (data) => {
+    .on(StreamingClient.EVENTS.DATA, (data: TranscriptEvent) => {
         const results = data.Transcript.Results
 
         if (!results || results.length === 0) {

src/types.ts

@@ -71,3 +71,29 @@ export interface AwsEventMessage {
     }
     body: Buffer
 }
+
+interface TranscribeItem {
+  Content: string,
+  EndTime: number,
+  StartTime: number,
+  Type: 'pronunciation' | 'punctuation'
+};
+
+interface TranscribeAlternative {
+  Items: Array<TranscribeItem>,
+  Transcript: string
+};
+
+interface TranscribeResult {
+  Alternatives: Array<TranscribeAlternative>,
+  EndTime: number,
+  IsPartial: Boolean,
+  ResultId: string,
+  StartTime: number
+};
+
+export interface TranscriptEvent {
+  Transcript: {
+    Results: Array<TranscribeResult>
+  }
+}