feat(fetch-requester): add @algolia/requester-fetch

[ykzts]

Edge Computing such as Cloudflare Worker and Edge Functions (Vercel) do not support XHR or Node.js HTTP modules. add a requester that uses Fetch and Edge Computing. Algolia's JS client can be used with Edge Computing by adding a requester that uses Fetch.

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[Haroenv]

First of all, thanks for this thorough pull request. It looks good on first glance, but I'll make sure to test it completely next week.

It makes sense for the future (even across major) to keep xhr as the default (as you've done here), as there's some other environments that don't have fetch (ie, react native)

[Haroenv]

this looks great and works as expected (sandbox that uses it: https://codesandbox.io/s/javascript-client-app-forked-iwbbje?file=/src/app.js). Some small nitpicks are all I have to add

[shortcuts]

Nothing to add, thanks a lot for the contribution!

[shortcuts]

Suggested change

	"cross-fetch": "^3.1.5",
	"cross-fetch": "3.1.5",

We can let renovate do the things

[my2ter]

Thanks for this!

Not sure if I'm missing something but unfortunately CloudFlare does not implement all parameters of the fetch api making it fails when I tried using it. I get a RetryError with the following:

The 'mode' field on 'RequestInitializerDict' is not implemented

If I comment out https://github.com/algolia/algoliasearch-client-javascript/blob/4.14.3/packages/requester-fetch/src/createFetchRequester.ts#L47 then it works.

Npm deps:

• "@algolia/requester-fetch": "^4.14.3",
• "algoliasearch": "^4.14.3"

Run locally: npx wrangler dev src/index.js
Code index.js:

import algoliasearch from 'algoliasearch';
import { createFetchRequester } from '@algolia/requester-fetch';

export default {
  async fetch(request) {
    return handleRequest(request)
  },
};

async function handleRequest(request) {
  const client = algoliasearch('APP_ID', 'SEARCH_KEY', {
    requester: createFetchRequester(),
  });

  const index = client.initIndex('index');
  let results = await index.search("a-search");

  return new Response(JSON.stringify(results), {
    headers: { 'content-type': 'application/json' },
  });
}

[shortcuts]

Hey @my2ter! we've change the order of the parameters in v5 (https://github.com/algolia/algoliasearch-client-javascript/blob/next/packages/requester-fetch/src/createFetchRequester.ts#L39-L49), which allows the user to override the value for the cors parameter, but it has not been reflected on v4.

If you wish to open the PR with the changes, please feel free! Otherwise I'll try to do it tomorrow