Lanuch Reactor API Rule Component creation for URL condition

I am coding Reactor API using node.js to create a new rule condition. 

This rule should fire when clicked <a href url contains a perticular pattern (eg. href="tel:123456" condition, href contains "tel:").

I have following API call as example:

....

attributes: {

name: 'click-event',

settings: JSON.stringify({

bubbleFireIfChildFired: true,

bubbleFireIfParent: true,

elementSelector: 'a#checkout'

}),

order: 0,

delegate_descriptor_id: 'core::events::click'

},
.......

What should the settings / elementSelector contain - so that this fires when URL contains a perticular patteren?
I am new to the API, hence apologies if I am asking a basic question.

Thanks in advance.

Regards