'keyCode' is deprecated.ts(6385)lib.dom.d.ts(14396, 8): The declaration was marked as deprecated here

Beacuse of event.keyCode is deprecated.
It means we are not supposed to use that code in our project.
Then how can we change code properly.

Before.

    document.addEventListener("keyup", (e) => {        
      if (e.keyCode == 37) {
          some code...
      }
    })

It should be updated like this.

    document.addEventListener("keyup", (e) => {        
      if (e.key == "ArrowLeft") {
          some code...
      }
    })

Then we have one question left, how can we know key name?
The easiest way is looking mdn.

https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent/key

See for youself.