JS: Optional Chaining Operator

By Xah Lee. Date: . Last updated: .

New in JS2020.

obj?.prop

Return the property value of object obj if it exist, but if obj is undefined or null or prop does not exist, return undefined.

💡 TIP: This is useful when you have a long chain such as a.b.c.d , and some property may not exist. With the normal dot notation, it would error out. 

console.log(undefined?.x === undefined);
console.log(null?.x === undefined);

// console.log(undefined.x);
// error: Uncaught TypeError: Cannot read property 'x' of undefined

const jj = {
  a1: 3,
  a3: { b1: 1, b3: 7 },
};

console.log(jj?.a2?.b3 === undefined);

JavaScript, Access Properties