Events

Events are signals, sent from Telegram native application in case, when some external action was done. Like methods, each event has its unique name and parameters.

Web

As mentioned before, the web version uses a standard way of communication between iframes. It means, the parent iframe is able to send events through window.postMessage function. To handle this type of message, it is enough to add message event listener on the global window object:

window.addEventListener('message', ...);

The native application will send an event with data: string which represents a JSON object converted to string. This object has the same interface as we defined in the Methods section:

interface MessageJSON {
  eventType: string;
  eventData: any;
}

Then, lets imagine how we could process an event from Telegram application:

window.addEventListener('message', ({ data }) => {
  const { eventType, eventData } = JSON.parse(data);
  console.log(eventType, eventData);
});

WARNING

In this code, we assumed, that the message event is sent only by the native application which is not always true in real applications. Additionally, we didn't check if data is really of type string. Don't forget to check each type and appropriately process incoming events.

Desktop, Mobile and Windows Phone

Desktop, mobile, and Windows Phone versions of Telegram don’t use the method, described in the previous section. They do it in a bit unusual way. The first thing developer should know, is in case, when Telegram needs to emit an event, it will insert JavaScript code, which calls a globally defined function.

Here is an example:

window.Telegram.WebView.receiveEvent('popup_closed', {
  button_id: 'cancel'
});

Path to this function depends on platform:

• window.TelegramGameProxy.receiveEvent - Telegram Desktop;
• window.Telegram.WebView.receiveEvent - Telegram for iOS and Android;
• window.TelegramGameProxy_receiveEvent - Windows Phone

All of these functions have the same signature:

type ReceiveEvent = (eventType: string, eventData: unknown) => void;

So, the solution is rather simple. To handle incoming events we should create a function of this type and assign it to all 3 paths.

Listening to Events

Handling all possible environments for a developer's application can be challenging. To simplify this process, the community developed the @telegram-apps/sdk package, which greatly eases integration.

Here's how to use it:

import { on } from '@telegram-apps/sdk';

// Start listening to "viewport_changed" event. Returned value
// is a function, which removes this event listener.
const removeListener = on('viewport_changed', payload => {
  console.log('Viewport changed:', payload);
});

// Remove this event listener.
removeListener();

You can learn more about calling methods in the package's documentation.

Available Events

This section contains the list of events, sent from Telegram: their names, description, and parameters. Section title means minimal version, from which events inside the section could be sent.

back_button_pressed

Available since: v6.1

User clicked the Back Button.

biometry_auth_requested

Available since: v7.2

Biometry authentication request completed. This event usually occurs in a response to the web_app_request_auth method.

If authentication was successful, the event contains a token from the local secure storage.

Field	Type	Description
status	'failed' or 'authorized'	Authentication status.
token	string	Optional. Token from the local secure storage saved previously. Passed only if status is authorized.

biometry_info_received

Available since: v7.2

Biometry settings were received.

Field	Type	Description
available	boolean	Shows whether biometry is available.
access_requested	boolean	Shows whether permission to use biometrics has been requested.
access_granted	boolean	Shows whether permission to use biometrics has been granted.
device_id	string	A unique device identifier that can be used to match the token to the device.
token_saved	boolean	Show whether local secure storage contains previously saved token.
type	'face' or 'finger'	The type of biometrics currently available on the device.

biometry_token_updated

Available since: v7.2

Biometry token was updated.

Field	Type	Description
status	updated or removed	Update status.

clipboard_text_received

Available since: v6.4

Telegram application attempted to extract text from clipboard.

Field	Type	Description
req_id	string	Passed during the web_app_read_text_from_clipboard method invocation req_id value.
data	string or null	Optional. Data extracted from the clipboard. The returned value will have the type string only in the case, application has access to the clipboard.

custom_method_invoked

Available since: v6.9

Custom method invocation completed.

Field	Type	Description
req_id	string	Unique identifier of this invocation.
result	unknown	Optional. Method invocation successful result.
error	string	Optional. Method invocation error code.

invoice_closed

An invoice was closed.

Field	Type	Description
slug	string	Passed during the  web_app_open_invoice  method invocation slug value.
status	string	Invoice status. Values: paid, invoice was paid failed, invoice failed pending, invoice is currently pending cancelled, invoice was cancelled

main_button_pressed

User clicked the Main Button.

phone_requested

Available since: v6.9

Application received phone access request status.

Field	Type	Description
status	string	Request status. Can only be sent.

popup_closed

Popup was closed.

Field	Type	Description
button_id	string	Optional. Identifier of the clicked button. In case, the popup was closed without clicking any button, this property will be omitted.

reload_iframe

Parent iframe requested current iframe reload.

qr_text_received

Available since: v6.4

The QR scanner scanned some QR and extracted its content.

Field	Type	Description
data	string	Optional. Data extracted from the QR.

scan_qr_popup_closed

Available since: v6.4

QR scanner was closed.

set_custom_style

The event which is usually sent by the Telegram web application. Its payload represents <style/> tag html content, a developer could use. The stylesheet described in the payload will help the developer to stylize the app scrollbar (but he is still able to do it himself).

settings_button_pressed

Available since: v6.1

Occurs when the Settings Button was pressed.

theme_changed

Occurs whenever the theme was changed in the user's Telegram app ( including switching to night mode).

Field	Type	Description
theme_params	Record<string, string>	Map where the key is a theme stylesheet key and value is the corresponding color in #RRGGBB format.

viewport_changed

Occurs whenever the viewport has been changed. For example, when the user started dragging the application or called the expansion method.

Field	Type	Description
height	number	The viewport height.
width	number	Optional. The viewport width.
is_expanded	boolean	Is the viewport currently expanded.
is_state_stable	boolean	Is the viewport current state stable and not going to change in the next moment.

TIP

Pay attention to the fact, that send rate of this method is not enough to smoothly resize the application window. You should probably use a stable height instead of the current one, or handle this problem in another way.

write_access_requested

Available since: v6.9

Application received write access request status.

Field	Type	Description
status	string	Request status. Can only be allowed.