javascript - Uncaught SyntaxError: Unexpected token '?'

Question

console.log(undefined ?? 'default');

Why am I getting an error Uncaught SyntaxError: Unexpected token '?'

Answer 1

Updated answer

The nullish-coalescing operator was added in ECMAScript 11.

The nullish coalescing operator (??) is a logical operator that returns its right-hand side operand when its left-hand side operand is null or undefined, and otherwise returns its left-hand side operand.

let x = undefined; 
console.log(x ?? 'default');

x = null; 
console.log(x ?? 'default');