How to use CustomEventData from Button in Cocos Creator 3.5.0?

Cocos Creator
#1

In the Button component we have CustomEventData. In my understanding the purpose it to send extra parameter when user tap the button.
image

I have tried to use it like this:

use_powerUp(par: string){
    console.log("MapScreenManager::use_powerUp() = ", par);
}

The Button will call the function and I thought the CustomEventData will be automatically become 1 parameter that will fill the par parameter. But turns out it didn’t.

Can anyone guide me how to properly use the CustomEventData?

#2

Did you read documentation ?
https://docs.cocos.com/creator/manual/en/ui-system/components/editor/button.html#add-a-callback-using-the-script

use_powerUp(event: Event, customEventData: string) {
         console.log(customEventData); // test1
     }