Odd behavior with asynchronous console I/O in REPL

[bbrk24]

Version

v16.15.0

Platform

Microsoft Windows NT 10.0.19044.0 x64

Subsystem

No response

What steps will reproduce the bug?

1. Open the REPL.
2. Run setTimeout(() => console.log('h'), 1000) and wait for the timer to expire. The letter h will print where the cursor was, and push the cursor down to the line after the prompt.
3. Type another letter which results in autofill, such as g. This already looks somewhat broken, with the letter appearing a few columns to the left of the cursor.
4. Hit tab to autofill. This is even more broken, as autofill picks up from the cursor rather than from the first letter.
5. Hit backspace and watch the word magically fix itself, with a new prompt in the same line as the cursor.

How often does it reproduce? Is there a required condition?

It always occurs when console.log is called asynchronously after the prompt is rendered. process.stdout.write also has somewhat odd behavior, but is noticeably less broken than console.log, possibly because of the lack of a newline character on the end.

What is the expected behavior?

It should be consistent with Promise.reject:

> Promise.reject('h')
Promise {
  <rejected> 'h',
  [Symbol(async_id_symbol)]: 96,
  [Symbol(trigger_async_id_symbol)]: 5,
  [Symbol(destroyed)]: { destroyed: false }
}
> Uncaught 'h'
>

Note that, although this does print Uncaught 'h' after the prompt, it then prints a new prompt immediately. With setTimeout and console.log, the new prompt isn't printed until backspace is pressed.

What do you see instead?

After step 3:

After step 4:

After step 5:

Additional information

Although I discovered this in v16.15.0, it also appears to happen in v14.19.2, v17.9.0, and v18.1.0.

[hemanth]

Ah, interesting. As you rightly pointed out process.stdout.write doesn't have this behavior.

If we just do a regular console.log on the REPL we see the undefined being logged on the screen which results in prompt.