Support using with ESM in browser

Currently there are no examples for using the project in the browser, so I created a minimal example that creates a connection in a web application bundled using Vite.js, which uses ES modules.

This does not work, for example because the library depends on globals.

This can be addressed by defining it (see this bug report):

<script>
  // @see https://github.com/aws/aws-sdk-js/issues/3673#issuecomment-855205181
  var global = global || window;
</script>

However then mqtt-packet/constants.js is loaded, which depends on the Node.js API. ESM and browser friendly alternative exists: https://www.npmjs.com/package/u8-mqtt-packet

I understand this is a bigger task, so I wanted people to have an issue to upvote.

[jmklix]

Thanks for bringing this to our attention. We want to add support for ESM, but I don’t have a date for when that will get added. Please continue to upvote if this is something that you want.

[bretambrose]

That is a very significant ask =/

That being said, we’re not super happy with the state of mqtt-js at the moment. Haven’t seen a reasonable alternative yet. Preliminary discussions about implementing a pure-JS client ourselves but that’s a lot of time for uncertain payoff.