promise/no-promise-in-callback

The code that calls a callback ignores what it returns. Nobody awaits a promise started inside one, so a rejection goes unhandled, and the code now reports errors in two different ways.

A function counts as a callback if its first parameter is named err or error. Inside one, the rule reports calls to then(), catch(), finally() and static methods such as Promise.all().

A call that's the value of a return statement isn't reported. A function passed to then() or catch() doesn't count as a callback, no matter what its first parameter is called.

Configure#

Off by default. To turn it on:

bunfig.toml

[lint.rules]
"promise/no-promise-in-callback" = "error" # or "warn"

Every option, set to its default:

bunfig.toml

[lint.rules]
"promise/no-promise-in-callback" = ["error", {
  exemptDeclarations = false,
}]

Examples#

example.js1 problem

fs.readFile(path, "utf8", (err, text) => {
  if (err) throw err;
  upload(text).then(notify);
});

example.jsNo problems

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

async function publish(path) {
  const text = await readFile(path, "utf8");
  await upload(text);
  notify();
}

upload(draft).catch(err => retry(draft).then(notify));

Options#

Option	Default	What it does
`exemptDeclarations`	`false`	Don't treat function declarations as callbacks, only function expressions and arrow functions.

example.js1 problem

function onFailure(error) {
  report(error).then(close);
}

example.jswith { "exemptDeclarations": true }No problems

function onFailure(error) {
  report(error).then(close);
}