`fs.write()` and `fs.writeFileSync()` coercion to string

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  • ¿Algo no está bien?
#412 2 comentarios 0 reacciones 0 asignados Ver en GitHub

Los mantenedores suelen responder en 2 días

@syhstanley ya está trabajando en esto.

Desde el 29/3/2026.

  • #416 de @syhstanley — abierto

Evaluación

Dificultad
4/5
Tiempo estimado
3-5 días
Aptitud para principiantes
48/100
Tipo de issue
Nueva funcionalidad
Claridad
Bastante claro
Estado de actividad
Tranquilo
Stack tecnológico
javascript, node.js, typescript
Área
tooling

Línea de trabajo

El payload no nombra archivos del repositorio, pruebas ni un punto de entrada de codemod; empieza por localizar el framework de migración existente y su cobertura de las APIs de fs de Node.js. Usa los métodos de fs enumerados, el ejemplo node:fs/promises y los casos válidos de Buffer y Uint8Array para definir la cobertura; después, verifica los cambios en la coerción de objetos sin alterar los tipos válidos.

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

Descripción

good first issue human help wanted let's do it

Description

Since implicit coercion of objects in fs.write() and fs.writeFileSync() is deprecated (DEP0162) and has reached End-of-Life status in Node.js v19.0.0, we should provide a codemod to replace them.

  • The codemod should convert objects with toString() method to primitive strings before passing to fs write functions.
  • The codemod should handle fs.write(), fs.writeFile(), fs.appendFile(), fs.writeFileSync(), and fs.appendFileSync().
  • The codemod should detect objects being passed as the data parameter.
  • The codemod should add explicit .toString() calls or String() conversion.

Additional Information

Note that in Node.js v19.0.0, implicit coercion of objects with own toString property passed as the second parameter (data) in fs write operations now throws an error. This was deprecated because the implicit conversion could lead to unexpected behavior and made the code less explicit.

Instead of relying on implicit coercion, developers should explicitly convert objects to strings using .toString(), String(), or template literals.

Examples

Example 1: Object in fs.writeFileSync()

Before:

const fs = require("node:fs");

const data = { toString: () => "file content" };
fs.writeFileSync("file.txt", data);

After:

const fs = require("node:fs");

const data = { toString: () => "file content" };
fs.writeFileSync("file.txt", data.toString());
Example 2: Object in fs.writeFile()

Before:

const fs = require("node:fs");

const obj = { toString: () => "content" };
fs.writeFile("file.txt", obj, (err) => {
  if (err) throw err;
});

After:

const fs = require("node:fs");

const obj = { toString: () => "content" };
fs.writeFile("file.txt", obj.toString(), (err) => {
  if (err) throw err;
});
Example 3: Object in fs.appendFileSync()

Before:

const fs = require("node:fs");

const data = { toString: () => "appended data" };
fs.appendFileSync("file.txt", data);

After:

const fs = require("node:fs");

const data = { toString: () => "appended data" };
fs.appendFileSync("file.txt", data.toString());
Example 4: Object in fs.appendFile()

Before:

const fs = require("node:fs");

const content = { toString: () => "more content" };
fs.appendFile("file.txt", content, (err) => {
  if (err) throw err;
});

After:

const fs = require("node:fs");

const content = { toString: () => "more content" };
fs.appendFile("file.txt", content.toString(), (err) => {
  if (err) throw err;
});
Example 5: Object in fs.write()

Before:

const fs = require("node:fs");

const fd = fs.openSync("file.txt", "w");
const data = { toString: () => "buffer content" };
fs.write(fd, data, (err) => {
  if (err) throw err;
  fs.closeSync(fd);
});

After:

const fs = require("node:fs");

const fd = fs.openSync("file.txt", "w");
const data = { toString: () => "buffer content" };
fs.write(fd, data.toString(), (err) => {
  if (err) throw err;
  fs.closeSync(fd);
});
Example 6: Using String() conversion

Before:

const fs = require("node:fs");

const myObj = {
  value: 42,
  toString() {
    return `Value: ${this.value}`;
  }
};
fs.writeFileSync("output.txt", myObj);

After:

const fs = require("node:fs");

const myObj = {
  value: 42,
  toString() {
    return `Value: ${this.value}`;
  }
};
fs.writeFileSync("output.txt", String(myObj));
Example 7: ESM with promises API

Before:

import { writeFile } from "node:fs/promises";

const data = { toString: () => "async content" };
await writeFile("file.txt", data);

After:

import { writeFile } from "node:fs/promises";

const data = { toString: () => "async content" };
await writeFile("file.txt", data.toString());
Example 8: Valid types (no change needed)

Before:

const fs = require("node:fs");

// These are all valid and don't need changes
fs.writeFileSync("file1.txt", "string");
fs.writeFileSync("file2.txt", Buffer.from("buffer"));
fs.writeFileSync("file3.txt", new Uint8Array([1, 2, 3]));

After:

const fs = require("node:fs");

// These are all valid and don't need changes
fs.writeFileSync("file1.txt", "string");
fs.writeFileSync("file2.txt", Buffer.from("buffer"));
fs.writeFileSync("file3.txt", new Uint8Array([1, 2, 3]));

Refs

Lenguaje dominante
TypeScript
Estrellas
85
Forks
58
Merge medio
1 d 21 h
PR fusionados (30 d)
8

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