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.