Optional chaining~ Basics ~

Optional chaining

My "favorite" error while I'm doing something with JavaScript is "Cannot read properties of undefined". Here's an example that produces that error:

const user = { name: 'Krasimir' };
// Uncaught TypeError: Cannot read properties of undefined (reading '0')

To prevent such situations, we do checks or use helpers. Reading values from deeply nested properties has always been a source of bugs. Today the language has a feature that solves this problem. It is called optional chaining. It provides safe access to nested fields. When something along the chain is undefined or null, the whole expression results in undefined. For example:

const user = { name: 'Krasimir' };
console.log(user?.skills?.[0]); // undefined