Node 14 - Optional chaining and nullish coalescing

Node 14

Node 14 is already released and will become the next LTS version during the last week of October 2020.

Node 14 is coming with two long awaited JS features, optional chaining and nullish coalescing. Let's check them out!

Optional chaining

Long gone will be the days of checking for the existence of a deeply nested property using the && operator or lodash.get.

The optional chaining operator is ?. and it permits accessing any nested property in a safe way with a single expression.

Example:

// Using the && operator
if (foo && foo.bar && foo.bar.baz) {
  // do something with foo.bar.baz
}

// Using the ?. operator
if (foo?.bar?.baz) {
  // do something with foo.bar.baz
}

Nullish coalescing

The nullish coalescing logical operator is ?? and it returns the right-hand side operand only if the left-hand side operand is null or undefined.

This sounds similar to the logical OR (||) operator, however the || operator returns the right-hand side operand when the left-hand side is any falsy value.

Thus for many cases that a default value has to be assigned only when a value is null or undefined, the nullish coalescing operator comes in handy.

Example:

const foo = 0;
console.log(foo || 10); // 10
console.log(foo ?? 10); // 0

const bar = false;
console.log(bar || true); // true
console.log(bar ?? true); // false

const baz = '';
console.log(baz || 'default'); // 'default'
console.log(baz ?? 'default'); // ''