While the function is available for testing in the new web version
The WhatsApp messenger development team has released an update to the web version of the application under the number 2.2319.9. While the new version is available for testing to some members of the WhatsApp Web beta program. The main innovation in it was a very useful ability to edit already sent messages. To make edits, you must select the Edit Post action from the menu for that post. You can edit text messages in both private and group chats.
WhatsApp now lets you edit a sent message
You can edit sent messages only during the first 15 minutes after sending, but an unlimited number of times. The developers note that the time limit is set to preserve the authenticity of the conversation and is designed to prevent the meaning of messages from changing over time. Mainly, the function is intended for correcting typos. So far, only the web version of WhatsApp supports the new feature, but soon it should appear in mobile applications.