Fix await download() when calling item.cancel() (#164)

Co-authored-by: Sindre Sorhus <sindresorhus@gmail.com>

index.d.ts

@@ -130,8 +130,18 @@ declare namespace electronDl {
 	}
 }
 
+/**
+Error thrown if `item.cancel()` was called.
+*/
+declare class CancelError extends Error {}
+
 // eslint-disable-next-line no-redeclare
 declare const electronDl: {
+	/**
+	Error thrown if `item.cancel()` was called.
+	*/
+	CancelError: typeof CancelError;
+
 	/**
 	Register the helper for all windows.
 
@@ -157,6 +167,8 @@ declare const electronDl: {
 	@param window - Window to register the behavior on.
 	@param url - URL to download.
 	@returns A promise for the downloaded file.
+	@throws {CancelError} An error if the user calls `item.cancel()`.
+	@throws {Error} An error if the download fails.
 
 	@example
 	```

index.js

@@ -5,6 +5,8 @@ const unusedFilename = require('unused-filename');
 const pupa = require('pupa');
 const extName = require('ext-name');
 
+class CancelError extends Error {}
+
 const getFilenameFromMime = (name, mime) => {
 	const extensions = extName.mime(mime);
 
@@ -92,10 +94,6 @@ function registerListener(session, options, callback = () => {}) {
 			item.setSavePath(filePath);
 		}
 
-		if (typeof options.onStarted === 'function') {
-			options.onStarted(item);
-		}
-
 		item.on('updated', () => {
 			receivedBytes = completedBytes;
 			for (const item of downloadItems) {
@@ -154,6 +152,7 @@ function registerListener(session, options, callback = () => {}) {
 				if (typeof options.onCancel === 'function') {
 					options.onCancel(item);
 				}
+				callback(new CancelError());
 			} else if (state === 'interrupted') {
 				const message = pupa(errorMessage, {filename: path.basename(filePath)});
 				callback(new Error(message));
@@ -182,6 +181,10 @@ function registerListener(session, options, callback = () => {}) {
 				callback(null, item);
 			}
 		});
+
+		if (typeof options.onStarted === 'function') {
+			options.onStarted(item);
+		}
 	};
 
 	session.on('will-download', listener);
@@ -214,3 +217,5 @@ module.exports.download = (window_, url, options) => new Promise((resolve, rejec
 
 	window_.webContents.downloadURL(url);
 });
+
+module.exports.CancelError = CancelError;

readme.md

@@ -50,7 +50,15 @@ const {download} = require('electron-dl');
 
 ipcMain.on('download-button', async (event, {url}) => {
  	const win = BrowserWindow.getFocusedWindow();
- 	console.log(await download(win, url));
+     try {
+         console.log(await download(win, url));
+     } catch (error) {
+         if (error instanceof electronDl.CancelError) {
+         	console.info('item.cancel() was called');
+		 } else {
+		 	console.error(error);
+		 }
+	 }
 });
 ```
 
@@ -128,7 +136,7 @@ Note: Error dialog will not be shown in `electronDl.download()`. Please handle e
 Type: `Function`
 
 Optional callback that receives the [download item](https://electronjs.org/docs/api/download-item).
-You can use this for advanced handling such as canceling the item like `item.cancel()`.
+You can use this for advanced handling such as canceling the item like `item.cancel()` which will throw `electronDl.CancelError` from the `electronDl.download()` method.
 
 #### onProgress