Ok, i think now i got you, after reading your suggestion once again…
let options = {
database: mainMenuDB,
limit: 100,
skip: 0
}
let resLimit = 'limit' in options;
console.log(resLimit); // true/false
resSkip = 'skip' in options;
console.log(resSkip); // true/false
EDIT: → TESTED → Works perfect → like expected!