WhatsApp released its web version a way back in 2015. WhatsApp web-only mirrors the conversation from the mobile app and the mobile should be connected to the internet. And the current desktop version of Whatsapp is not fully efficient.
But the current scenario may change as Reliable WhatsApp leaker account WABetainfo has tweeted something related to the upcoming WhatsApp desktop version. In his tweet, he said that the company might be developing a Universal Windows Platform (UWP) along with a multi-platform system. The upcoming version of WhatsApp will work even when the phone is switched off.
If this happens then you will be able to access WhatsApp from your desktop without having your phone with you. You will not be required to authorize every time from your phone to use WhatsApp on your desktop.
Currently, WhatsApp allows its users to use it on Windows or MAC desktop. But the major disadvantage is that you need to have your phone with you to access WhatsApp on the desktop. Telegram has already launched its desktop version which doesn't require user's phone to run. However, there is no solid information when this feature will be available for WhatsApp users. Stay tuned here to find future information regarding this.