Regular Expression Subscriptions

Regular Expression (Regex) subscriptions allow a regular expression to be supplied in the place of a topic name. When you supply a regular expression, it is as if a subscription is made to every topic that matches your expression, including topics that do not yet exist at the time of creating the subscription.

To use a regular expression, simply supply the regular expression in place of the topic name in the subscribe() call. For example:

await client.subscribe(message => { ... }, 'orders.*');

In this example, messages on topics `orders-north-america`,
`orders-europe`, and `new-orders` would match the regular expression,
and those messages would all be sent to the message handler function.
As in the example, you can use the `message.header.topic()` method to
determine the actual topic of the message sent to the function.