modern-javascript-patterns

Wrap callback-based operations in Promises, then consume them with async/await inside try/catch blocks for error handling. For independent operations, run them in parallel with Promise.all instead of awaiting sequentially.

Use the spread operator to create new objects with updated properties, such as { ...user, age: 31 }. For arrays, use map, filter, and spread instead of push or splice to avoid mutating the original data.

Promise.all rejects as soon as any promise fails, while Promise.allSettled waits for all promises and returns each result with a fulfilled or rejected status. Use allSettled when partial results are acceptable.

Yes, they combine well: user?.address?.city ?? 'unknown' safely accesses nested properties and provides a default only for null or undefined. Unlike ||, the ?? operator preserves falsy values like 0 and empty strings.

Avoid arrow functions when you need dynamic this binding, such as object methods that reference the instance, prototype methods, or event handlers relying on the target element. Arrow functions inherit this lexically from the enclosing scope.