You can add custom events to the components dynamically by using the addEventHandler() method in the component object.

The syntax for a custom event is as follows:

addEventHandler(String event, Function handler, String phase, String includeFacets) 

The following provides a description for each of the parameters of the addEventHandler component method:

• The first argument is the name of the event that triggers the handler. The <aura:registerEvent> tag in a component's markup declares the event that the component fires.

• The second argument is the action that handles the event. The format is similar to the value that you would put in the action attribute in the <aura:handler> tag, if the handler was statically defined in the markup. There are two options for this argument.
• To use a controller action in the handler, use the following format:

cmp.getReference("c.actionName")

• To use an anonymous function, use the following format:
  

function(auraEvent) {
 // handling logic here
 }