nodejs / nodejs/node

Odd behavior with asynchronous console I/O in REPL

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#43,074 1 comentario 1 reacción 0 asignados Ver en GitHub

Nadie ha tomado este issue todavía.

confirmed-bug repl
Lenguaje dominante
JavaScript
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Merge medio
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PR fusionados (30 d)
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Descripción

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:
image
After step 4:
image
After step 5:
image

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.

Guía de contribución

Abrir la guía de contribución

Primeros pasos

  1. Lee el issue completo y luego la guía de contribución del proyecto.
  2. Comenta en el issue que vas a ocuparte — evita que dos personas hagan lo mismo.
  3. Haz un fork del repositorio y trabaja en una rama.
  4. Abre un pull request que haga referencia al número del issue.

Línea de trabajo

Reproduce el problema en el REPL de Node.js usando setTimeout con console.log y, a continuación, rastrea la E/S asíncrona de la consola del REPL y la gestión del prompt. Se considerará completado cuando la salida asíncrona deje un prompt coherente y conserve el comportamiento al escribir, al autocompletar y al usar la tecla de retroceso, como en el ejemplo Promise.reject.

Escrito por el modelo de indexación a partir del texto del issue.

Evaluación

Stack tecnológico
javascript
Área
cli
Tipo de issue
Error
Dificultad
4/5
Tiempo estimado
3-5 días
Estado de actividad
Estancado
Claridad
Bastante claro
Aptitud para principiantes
35/100

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