Get key value of jason Object with javascript

I have a json file with the following object:

{
  "month": "April",
  "events" : [
      "event 1",
      "event 2"     
   ] ,

"event 1": [
          "1.3",
          "2.3",
          "3.3",
          "4.3"
 ],
"event 2": [
  "7.3",
  "16.3"
 ]
}

I’d like to get the key of the Object for further transactions.

let datesOfEvents = [];
var jSObject = getData().then((a) =>{   

            for (let i = 0; i<a.length;i++){
                
                    if(typeof a[i].events !== 'undefined'){
                         
                        for (let key in a[i] ){
                                        
                            if (key == "event1"){
                                    datesOfEvents = a[i].key;   

                            }
                        }   

                   }
                }
             })

As the key value, I’m asking for in the if statement is a String, I cannot call the other values this way a[i].key. when I call them individually, like this:

datesOfEvents = a[i].event1; 

it works fine. My question is: what type do I have to query in the if statement to get the values of event1?