lb-fetch


A load balanced fetch.

Installation

``bash
npm i lb-fetch
`

Usage

`javascript
import lbFetch from 'lb-fetch';

const response = await lbFetch(
[
"https://server1.example.com/api/endpoint",
new URL("https://server2.example.com/api/endpoint")
],
{
method: 'POST',
body: new URLSearchParams({
foo: 'bar',
baz: '42'
})
}
);
`

API

$3

Tries to fetch one of the inputs in some order until successful.

Returns a Promise of a
Response.

#### input

Type: (string | URL)[] _or_ generic InputType[]

The URLs to try. The input may also be an array of anything else, then
options.balancer must be defined.

#### init

Type: RequestInit | undefined

Default: undefined

Same as
fetch options.

#### options.fetch

Type: typeof fetch

Default: the global fetch method

Any method that conforms to
the Fetch API.

#### options.balancer

Type: Balancer

`typescript
type Balancer = (
inputs: InputType[],
init: RequestInit | undefined
) => Promise<(string | URL)[]> | (string | URL)[];
`

Default: randomBalancer

This method decides the order in which the entries of input are tried.

Note: the default value only works for inputs consisting of strings and
URLs.

#### options.success

Type: SuccessPredicate

`typescript
type SuccessPredicate = (response: Response) => boolean;
`

Default: reject500s

This method decides whether an attempt was successful.

If a request to an input throws an exception, it is also considered unsuccessful.

$3

The default balancer returns a shuffled shallow copy of its input.

#### input

Type: (string | URL)[]

$3

The default SuccessPredicate accepts a response, if its status is less than
500` – i.e. if the response was not a server error.