CORS

This framework is a helper framework that wraps around another framework and gets some options to configure CORS in your app using the cors library behind the scenes.

Why?

Why should I use this framework instead of directly using my framework/application's joe-doe-cors package?

Using this framework, you can skip the request to your framework, so it's faster to handle it directly in the library instead of leaving it to your frame.

Also, frameworks like trpc, deepḱit and other frameworks don't have a good way of dealing with CORS, so with CorsFramework you can do the CORS works for these frameworks.

Finally, I added an optimization, inspired by access control, which returns the Forbidden error when the origin is invalid or when the method is not allowed. In other packages, like fastify/cors, the cors itself used by this library and even other languages, they process the request if the origin is invalid and to me it sounds like a waste of resources, so we can just return the error to the user instead of processing the request which is sure to return the error in the user's browser.

If you want to disable this behaviour, set { forbiddenOnInvalidOriginOrMethod: false } in the options.

Requirements

To be able to use, first you need to install some packages:

npm i --save cors

If you are using TypeScript:

npm i --save-dev @types/cors

Usage

The first parameter is the instance of another framework, so if you want to use Express for example, you can just use like this:

import { ServerlessAdapter } from '@h4ad/serverless-adapter';
import { CorsFramework, CorsFrameworkOptions } from '@h4ad/serverless-adapter/frameworks/cors';
import { ExpressFramework } from '@h4ad/serverless-adapter/frameworks/express';

const express = require('express');

const expressFramework = new ExpressFramework();
// see docs about the options in the original package:
// https://github.com/expressjs/cors
const options: CorsFrameworkOptions = { origin: '*' };
const framework = new CorsFramework(expressFramework, options);

export const handler = ServerlessAdapter.new(express)
  .setFramework(framework)
  // continue to set the other options here.
  //.setHandler(new DefaultHandler())
  //.setResolver(new PromiseResolver())
  //.addAdapter(new AlbAdapter())
  //.addAdapter(new SQSAdapter())
  //.addAdapter(new SNSAdapter())
  // after put all methods necessary, just call the build method.
  .build();

tip

Is your application instance creation asynchronous? Look the LazyFramework which helps you in asynchronous startup.