mojo/public/mojom/base/jserror.mojom

// Copyright 2025 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

module mojo_base.mojom;

// Represents an error on the javascript side. All mojo interfaces hosted
// in javascript that declares a result<T, E> return should use JsError for
// their E parameter. Users are strongly discouraged against defining their
// own E type in javascript because errors are typically loosely typed
// in javascript. If mojo is unable to map the error emitted in javascript
// to a wire format, mojo will close the pipe to avoid undefined
// behaviour.
//
// JsError is primarily designed to propagate javascript Error objects to
// the receiver, but is able to accept any javascript object as the input.
//
// Note that while JsError is able to *encode* any javascript object into
// a mojo object, this does not mean that all details of a javascript
// object will be propagated to the receiver. It will only read the
// {name, cause, message} fields in the input object.
struct JsError {
  string? name;
  string? cause;
  // The primary method to communicate failures to the receiving end.
  // Maps to the message field of the object. If no message is provided,
  // an unknown error message is set. There is no guarantee about the unknown
  // error message or its shape, besides that it is be set.
  string? message;
};