Check If An Object Contains A Property

Category: JavaScript

const symbol = Symbol("a");

const obj = {
  propOne: 1,
  [symbol]: 2,
};

"propOne" in obj; // true
symbol in obj; // true
0 in obj; // false

Explanation

The in operator specifically checks whether an object has a specific key. So, instead of accessing the property and checking whether it is undefined, you can better mark your intent by just using in.