Why doesn't the in operator work with the list of strings in JavaScript

Question

let checkExistance = "a" in ["a","b","c","e"];

console.log(checkExistance)// returns false

// wh`your text`y 

/I tried the in operator in JavaScript to create a function that takes two parameters an object and property to be removed. I used the in operator to check if the item or property I want to remove exists or not. But the in operator behaves diffently./