aggregate-error

What is aggregate-error?

The aggregate-error package is used to create an Error instance that aggregates multiple errors into a single error object. This can be useful when you have several operations that may each throw errors, and you want to collect all of those errors into a single error object that can be thrown, returned, or logged.

What are aggregate-error's main functionalities?

Aggregating multiple errors

This feature allows you to collect multiple errors into a single error object. The code sample demonstrates how to create an instance of AggregateError with an array of Error objects and then throw it.

const AggregateError = require('aggregate-error');

const errors = [
  new Error('First error'),
  new Error('Second error')
];

const aggregatedError = new AggregateError(errors);

throw aggregatedError;

Iterating over aggregated errors

This feature allows you to iterate over the individual errors within an AggregateError instance. The code sample shows how to loop through each error using a for...of loop and log them to the console.

const AggregateError = require('aggregate-error');

const errors = [
  new Error('First error'),
  new Error('Second error')
];

const aggregatedError = new AggregateError(errors);

for (const error of aggregatedError) {
  console.error(error);
}

Other packages similar to aggregate-error

verror

The verror package provides a way to create rich JavaScript errors. It allows you to chain errors, add context to them, and format multi-line error messages. It is similar to aggregate-error in that it helps manage multiple error objects, but it focuses more on providing additional context and information about single errors rather than aggregating multiple errors.

multi-error

Multi-error is another package that allows you to combine multiple errors into a single error object. It is similar to aggregate-error, but it has a different API and additional features such as filtering and mapping over the contained errors.

README

aggregate-error

Create an error from multiple errors

Note: With Node.js 15, there's now a built-in AggregateError type.

Install

$ npm install aggregate-error

Usage

import AggregateError from 'aggregate-error';

const error = new AggregateError([new Error('foo'), 'bar', {message: 'baz'}]);

throw error;
/*
AggregateError:
    Error: foo
        at Object.<anonymous> (/Users/sindresorhus/dev/aggregate-error/example.js:3:33)
    Error: bar
        at Object.<anonymous> (/Users/sindresorhus/dev/aggregate-error/example.js:3:13)
    Error: baz
        at Object.<anonymous> (/Users/sindresorhus/dev/aggregate-error/example.js:3:13)
    at AggregateError (/Users/sindresorhus/dev/aggregate-error/index.js:19:3)
    at Object.<anonymous> (/Users/sindresorhus/dev/aggregate-error/example.js:3:13)
    at Module._compile (module.js:556:32)
    at Object.Module._extensions..js (module.js:565:10)
    at Module.load (module.js:473:32)
    at tryModuleLoad (module.js:432:12)
    at Function.Module._load (module.js:424:3)
    at Module.runMain (module.js:590:10)
    at run (bootstrap_node.js:394:7)
    at startup (bootstrap_node.js:149:9)
*/

for (const individualError of error.errors) {
	console.log(individualError);
}
//=> [Error: foo]
//=> [Error: bar]
//=> [Error: baz]

API

AggregateError(errors)

Returns an Error.

errors

Type: Array<Error|object|string>

If a string, a new Error is created with the string as the error message.
If a non-Error object, a new Error is created with all properties from the object copied over.