Optional Chaining

OptionalChaining.js

// without Optional Chaining
function sayHi(user) {
   let name = (user && user.name && user.name.toUpperCase()) || "Unknown";
    console.log(`Hi Mr. ${name}`);
}
sayHi({}); // Hi Mr. Unknown
sayHi(); // Hi Mr. Unknown

// with Optional Chaining
function sayHi(user) {
   let name = ( user?.name?.toUpperCase?.() ) || "unKnown";
   console.log(`Hi Mr. ${name}`);
}

// (property == undefined || property == null) ? undefined : property
// Optional Chaining systax
// obj?.prop
// obj?.[expr]
// arr?.[index]
// func?.(args)

Optional chaining MDN