An attempt to use web3.js errors out with "Request has been blocked by CORS policy"

Use WebsocketProvider as HttpProvider is deprecated

Issue

An attempt to use web3.js with an Ethereum node fails with the following error:

Access to XMLHttpRequest at 'https://user-name:[email protected]' from origin 'http://12.345.67.890' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource.

Cause

You are attempting to use a deprecated HttpProvider.

There is no CORS policy for WebSocket.

Solution

Use WebsocketProvider, which is the standard for web3.js.

See also Chainstack Docs: web3.js.