JavaScript – Nullish coalescing operator (??)

Last updated on January 30, 2021

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.

const foo = null ?? 'default string';
console.log(foo);
// expected output: "default string"

const baz = 0 ?? 42;
console.log(baz);
// expected output: 0

const bar = undefined ?? 'default string';
console.log(bar);
// expected output: default string