node/callback-return Style
What it does
Require return statements after callbacks.
Why is this bad?
This rule is aimed at ensuring that callbacks used outside of the main function block are always part-of or immediately preceding a return statement. This rule decides what is a callback based on the name of the function being called.
Examples
Examples of incorrect code for this rule:
function done(err) {
if (err) {
callback(err);
}
callback();
}Examples of correct code for this rule:
function done(err) {
if (err) {
return callback(err);
}
callback();
}Known Limitations
Because it is difficult to understand the meaning of a program through static analysis, this rule has limitations:
- false negatives when this rule reports correct code, but the program calls the callback more than one time (which is incorrect behavior)
- false positives when this rule reports incorrect code, but the program calls the callback only one time (which is correct behavior)
Passing the callback by reference
The static analysis of this rule does not detect that the program calls the callback if it is an argument of a function (for example, setTimeout).
Example of a false negative when this rule reports correct code:
function foo(err, callback) {
if (err) {
setTimeout(callback, 0); // this is bad, but WILL NOT warn
}
callback();
}Triggering the callback within a nested function
The static analysis of this rule does not detect that the program calls the callback from within a nested function or an immediately-invoked function expression (IIFE).
Example of a false negative when this rule reports correct code:
function foo(err, callback) {
if (err) {
process.nextTick(function () {
return callback(); // this is bad, but WILL NOT warn
});
}
callback();
}If/else statements
The static analysis of this rule does not detect that the program calls the callback only one time in each branch of an if statement.
Example of a false positive when this rule reports incorrect code:
function foo(err, callback) {
if (err) {
callback(err); // this is fine, but WILL warn
} else {
callback(); // this is fine, but WILL warn
}
}Configuration
The rule takes a single option - an array of possible callback names - which may include object methods. The default callback names are callback, cb, next.
type: string[]
default: []
How to use
To enable this rule using the config file or in the CLI, you can use:
{
"plugins": ["node"],
"rules": {
"node/callback-return": "error"
}
}import { defineConfig } from "oxlint";
export default defineConfig({
plugins: ["node"],
rules: {
"node/callback-return": "error",
},
});oxlint --deny node/callback-return --node-pluginVersion
This rule was added in vnext.