Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

doc: document ES2022's Error "cause" property #43830

Merged
merged 4 commits into from
Jul 16, 2022
Merged
Changes from all commits
Commits
File filter

Filter by extension

Filter by extension

Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
51 changes: 49 additions & 2 deletions doc/api/errors.md
Original file line number Diff line number Diff line change
Expand Up @@ -191,13 +191,16 @@ provide a text description of the error.
All errors generated by Node.js, including all system and JavaScript errors,
will either be instances of, or inherit from, the `Error` class.

### `new Error(message)`
### `new Error(message[, options])`

* `message` {string}
* `options` {Object}
* `cause` {any} The error that caused the newly created error.

Creates a new `Error` object and sets the `error.message` property to the
provided text message. If an object is passed as `message`, the text message
is generated by calling `message.toString()`. The `error.stack` property will
is generated by calling `String(message)`. If the `cause` option is provided,
it is assigned to the `error.cause` property. The `error.stack` property will
represent the point in the code at which `new Error()` was called. Stack traces
are dependent on [V8's stack trace API][]. Stack traces extend only to either
(a) the beginning of _synchronous code execution_, or (b) the number of frames
Expand Down Expand Up @@ -253,6 +256,49 @@ will affect any stack trace captured _after_ the value has been changed.
If set to a non-number value, or set to a negative number, stack traces will
not capture any frames.

### `error.cause`

<!-- YAML
added: v16.9.0
-->

* {any}

If present, the `error.cause` property is the underlying cause of the `Error`.
It is used when catching an error and throwing a new one with a different
message or code in order to still have access to the original error.

The `error.cause` property is typically set by calling
`new Error(message, { cause })`. It is not set by the constructor if the
`cause` option is not provided.

This property allows errors to be chained. When serializing `Error` objects,
[`util.inspect()`][] recursively serializes `error.cause` if it is set.

```js
const cause = new Error('The remote HTTP server responded with a 500 status');
const symptom = new Error('The message failed to send', { cause });

console.log(symptom);
// Prints:
// Error: The message failed to send
// at REPL2:1:17
// at Script.runInThisContext (node:vm:130:12)
// ... 7 lines matching cause stack trace ...
// at [_line] [as _line] (node:internal/readline/interface:886:18) {
// [cause]: Error: The remote HTTP server responded with a 500 status
// at REPL1:1:15
// at Script.runInThisContext (node:vm:130:12)
// at REPLServer.defaultEval (node:repl:574:29)
// at bound (node:domain:426:15)
// at REPLServer.runBound [as eval] (node:domain:437:12)
// at REPLServer.onLine (node:repl:902:10)
// at REPLServer.emit (node:events:549:35)
// at REPLServer.emit (node:domain:482:12)
// at [_onLine] [as _onLine] (node:internal/readline/interface:425:12)
// at [_line] [as _line] (node:internal/readline/interface:886:18)
```

### `error.code`

* {string}
Expand Down Expand Up @@ -3514,6 +3560,7 @@ The native call from `process.cpuUsage` could not be processed.
[`subprocess.send()`]: child_process.md#subprocesssendmessage-sendhandle-options-callback
[`url.parse()`]: url.md#urlparseurlstring-parsequerystring-slashesdenotehost
[`util.getSystemErrorName(error.errno)`]: util.md#utilgetsystemerrornameerr
[`util.inspect()`]: util.md#utilinspectobject-options
[`util.parseArgs()`]: util.md#utilparseargsconfig
[`v8.startupSnapshot.setDeserializeMainFunction()`]: v8.md#v8startupsnapshotsetdeserializemainfunctioncallback-data
[`zlib`]: zlib.md
Expand Down