RestClient

RestClient provides a clean, flexible abstraction to interact with RESTful APIs via HTTP methods. It supports GET, POST, PUT, PATCH, and DELETE requests with JSON or text response handling, customizable headers, request timeout, and optional retries for transient errors.

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Features

• Supports GET, POST, PUT, PATCH, and DELETE methods.
• Automatically handles JSON and text responses.
• Customizable default headers.
• Configurable timeout and retry mechanism.
• Lifecycle hooks for logging or custom behaviors.
• Clean URL and query parameter handling.

Constructor

constructor(
  baseUrl: string,
  defaultHeaders?: Record<string, string>,
  options?: RestClientOptions
)

• baseUrl: Base URL for all API requests (e.g., https://api.example.com).
• defaultHeaders: Optional default headers included in every request.
• options: Configuration such as timeout, max retries, retry policy, delay function, and hooks through RestClientOptions.

Parameters

Parameter	Type	Description
baseUrl	string	The base URL for all API requests (e.g., https://api.example.com).
defaultHeaders	Record<string, string>	Optional headers included in every request. Default includes Content-Type: application/json.
options	RestClientOptions	Optional configuration to control timeout, retries, and request hooks.

Example

const client = new RestClient("https://api.example.com", {
  Authorization: "BEARER_TOKEN"
}, {
  timeout: 15000,
  maxRetries: 2,
  onRequestStart: (method, url) => console.log(`Starting ${method} ${url}`)
});

Internal Behavior

Default Headers

All requests include:

{
  "Content-Type": "application/json",
  ...yourHeaders
}

Timeout

Requests time out after the specified duration (default: 10000ms).

Retry Logic

If enabled (maxRetries > 0), failed requests will be retried based on:

shouldRetry: (res) => [502, 503, 504].includes(res.status)

You can override this by providing a custom shouldRetry function.

Delay Function

The delay between retries can be customized with the delayFn. By default, it uses:

(ms) => new Promise(resolve => setTimeout(resolve, ms))

Or you can plug in your own exponential backoff implementation.

Lifecycle Hooks

These optional hooks provide fine-grained control or logging over the request lifecycle:

Hook	Signature	Description
onRequestStart	(method: string, url: string, options: RequestInit)	Called before sending a request.
onRequestEnd	(response: Response)	Called after a successful response.
onRequestError	(error: unknown)	Called when a request fails due to an exception.

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Methods

The RestClient class provides the following async methods:

Method	Description	Returns	Link
setHeaders	Updates default headers (e.g. Authorization).	void	setHeaders
getAsync	Sends a GET request with optional query params.	Promise<any>	getAsync
postAsync	Sends a POST request with a JSON body.	Promise<any>	postAsync
putAsync	Sends a PUT request with a JSON body.	Promise<any>	putAsync
patchAsync	Sends a PATCH request with a JSON body.	Promise<any>	patchAsync
deleteAsync	Sends a DELETE request.	Promise<any>	deleteAsync

Each method supports optional headers and AbortController for cancellation.

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