improve typescript

index.d.ts

@@ -13,11 +13,18 @@ type SetHeaders = (h: DownloadHeaders) => void;
 
 export interface TaskInfoObject {
   id: string;
-  percent: number;
-  bytesWritten: number;
-  totalBytes: number;
+  metadata: object | string;
+
+  percent?: number;
+  bytesWritten?: number;
+  totalBytes?: number;
+
+  beginHandler?: Function;
+  progressHandler?: Function;
+  doneHandler?: Function;
+  errorHandler?: Function;
 }
-export type TaskInfo = string | TaskInfoObject;
+export type TaskInfo = TaskInfoObject;
 
 export interface BeginHandlerObject {
   expectedBytes: number;

index.ts

@@ -1,5 +1,6 @@
 import { NativeModules, NativeEventEmitter } from 'react-native'
-import DownloadTask from './lib/downloadTask'
+import DownloadTask from './lib/DownloadTask'
+
 const { RNBackgroundDownloader } = NativeModules
 const RNBackgroundDownloaderEmitter = new NativeEventEmitter(RNBackgroundDownloader)
 
@@ -43,7 +44,9 @@ export function checkForExistingDownloads () {
   return RNBackgroundDownloader.checkForExistingDownloads()
     .then(foundTasks => {
       return foundTasks.map(taskInfo => {
+        // SECOND ARGUMENT RE-ASSIGNS EVENT HANDLERS
         const task = new DownloadTask(taskInfo, tasksMap.get(taskInfo.id))
+
         if (taskInfo.state === RNBackgroundDownloader.TaskRunning) {
           task.state = 'DOWNLOADING'
         } else if (taskInfo.state === RNBackgroundDownloader.TaskSuspended) {
@@ -79,22 +82,33 @@ export function completeHandler (jobId) {
   return RNBackgroundDownloader.completeHandler(jobId)
 }
 
-export function download (options) {
+type DownloadOptions = {
+  id: string,
+  url: string,
+  destination: string,
+  headers?: object,
+  metadata?: object,
+}
+
+export function download (options : DownloadOptions) {
   if (!options.id || !options.url || !options.destination)
     throw new Error('[RNBackgroundDownloader] id, url and destination are required')
 
   options.headers = { ...headers, ...(options.headers || {}) }
 
-  options.metadata = JSON.stringify(
-    options.metadata && typeof options.metadata === 'object'
-      ? options.metadata
-      : {}
-  )
+  if (!(options.metadata && typeof options.metadata === 'object'))
+    options.metadata = {}
 
-  const task = new DownloadTask({ id: options.id, metadata: options.metadata })
+  const task = new DownloadTask({
+    id: options.id,
+    metadata: options.metadata,
+  })
   tasksMap.set(options.id, task)
 
-  RNBackgroundDownloader.download(options)
+  RNBackgroundDownloader.download({
+    ...options,
+    metadata: JSON.stringify(options.metadata),
+  })
 
   return task
 }

lib/DownloadTask.ts

@@ -1,4 +1,6 @@
 import { NativeModules } from 'react-native'
+import { TaskInfo } from '..'
+
 const { RNBackgroundDownloader } = NativeModules
 
 function validateHandler (handler) {
@@ -9,13 +11,15 @@ function validateHandler (handler) {
 }
 
 export default class DownloadTask {
+  id = ''
   state = 'PENDING'
+  metadata = {}
+
   percent = 0
   bytesWritten = 0
   totalBytes = 0
-  metadata = {}
 
-  constructor (taskInfo, originalTask) {
+  constructor (taskInfo: TaskInfo, originalTask?: TaskInfo) {
     this.id = taskInfo.id
     this.percent = taskInfo.percent ?? 0
     this.bytesWritten = taskInfo.bytesWritten ?? 0