I am manipulating an obj, so that it can be dispatched using redux, by using foll code.

const objMap = {};
const propList = ['apple', 'banana'];

for (const prop of propList) {
   objMap[prop] = 0;
}
console.log("thunk2: ", materialMap);
dispatch(reduxActions.updateCount({ objMap }));

without dispatch(); line of code, result is

{
  "apple": 0,
  "banana": 0,
}

but when dispatch() is used then result is as below with extra property 'undefined'

{
    "apple": 0,
    "banana": 0,
    "undefined": null
}

why is 'undefined' being added?