node/handle-callback-err Restriction

What it does

This rule expects that when you're using the callback pattern in Node.js you'll handle the error.

Why is this bad?

In Node.js, a common pattern for dealing with asynchronous behavior is called the callback pattern. This pattern expects an Error object or null as the first argument of the callback. Forgetting to handle these errors can lead to some really strange behavior in your application.

function loadData(err, data) {
  doSomething(); // forgot to handle error
}

Examples

Examples of incorrect code for this rule with the default "err" parameter name:

function loadData(err, data) {
  doSomething();
}

Examples of correct code for this rule with the default "err" parameter name:

function loadData(err, data) {
  if (err) {
    console.log(err.stack);
  }
  doSomething();
}

function generateError(err) {
  if (err) {
  }
}

Examples of correct code for this rule with a sample "error" parameter name:

function loadData(error, data) {
  if (error) {
    console.log(error.stack);
  }
  doSomething();
}

Configuration

The rule takes a single string option: the name of the error parameter.

This can be either:

an exact name (e.g. "err", "error")
a regexp pattern (e.g. "^(err|error)$")

If the configured name of the error variable begins with a ^ it is considered to be a regexp pattern.

Default: "err".

type: string

How to use

To enable this rule using the config file or in the CLI, you can use:

Config (.oxlintrc.json)Config (oxlint.config.ts)CLI

json

{
  "plugins": ["node"],
  "rules": {
    "node/handle-callback-err": "error"
  }
}

import { defineConfig } from "oxlint";

export default defineConfig({
  plugins: ["node"],
  rules: {
    "node/handle-callback-err": "error",
  },
});

bash

oxlint --deny node/handle-callback-err --node-plugin

Version

This rule was added in v1.56.0.

What it does ​

Why is this bad? ​

Examples ​

Configuration ​

How to use ​

Version ​