Rest Error

Independently of the chosen API Style, probably you will have to deal with errors, to provide an efficient way to track errors, in Scarlett you will find a utility class named RestError that extends the default JavaScript's Error.

It is used internally to track and better qualify the error thrown.

Sometimes, a success response body differs from error response body, for this reason you can specify generic types qualify the response provided by backend API's handled exceptions:

const response = await rest.get<any, IBackendError>("/status-code/412");
const data = response.data;         // << response.data property inferred as null because of the error
const error = response.error?.data; // << error.data property inferred as IBackendError

When a request's response has an error, you will find an instance of RestError as a property named error on IResponse object. If the throw flag is enabled, or the throwExcluding fails to filter an error, the library will internally throw it.

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You can even import it and create an instance to extend your business logic:

import { RestError } from "scarlett";
const err = new RestError<IBackendError>("The Error Message");

constructor

(message: string, statusCode?: HTTPStatusCode, code?: InternalErrorCode)

message

type message = string

A human-friendly error message.

statusCode

enum HTTPStatusCode {}

An enum containing all the standard http status codes.

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You can import this enum from Scarlett and use it in your app:

import { HTTPStatusCode } from "scarlett"

code

type InternalErrorCode = "Timeout" | "BodyParse" | "UrlParameter";

An internal error code to track unexpected behaviors based on request settings.

INFO

Any of these parameters are available as public properties on RestError instance.

isRestError

An always true property, used as simple utility to distinguish the standard Error from the RestError.

request

The request object use to perform the request, it is just the same type defined on the response object.

fetchResponse

Instance of type Response, the native response object from the Fetch API.

data

The error object parsed from response body content, inferred with the type provided as generic in the request method or when creating a new instance.