JSFiddle - React, Tailwind, and code Playground

JavaScript

function DynamicKey(){
   
   var keys = {};
   
   var _obj = {
     inc:function(key){
        if(!keys.hasOwnProperty(key)){
            keys[key] = 0;
        }
        keys[key] += 1;
        return _obj;
     },
     get:function(key){
       return keys[key];
     }
   }
   return _obj;
}

var d = DynamicKey();
d.inc('key1').inc('key1').inc('key2').inc('key3').inc('key1').inc('key2');

console.log("key1 count => ", d.get('key1'));
console.log("key2 count => ", d.get('key2'));
console.log("key3 count => ", d.get('key3'));