15 JavaScript Tips That Will Make You a Better Developer in 2026

These JavaScript tips have genuinely improved my code quality. No fluff — just patterns that work. 1. Optional Chaining is Your Best Friend // Old way - ugly and error-prone const city = user && user . address && user . address . city ; // Modern way const city = user ?. address ?. city ; // With methods const first = arr ?. at ( 0 ); const len = str ?. trim ()?. length ; 2. Nullish Coalescing vs OR // || uses any falsy value (0, '', false are falsy!) const count = data . count || 10 ; // BUG: returns 10 when count is 0 // ?? only triggers on null/undefined const count = data . count ?? 10 ; // CORRECT: returns 0 when count is 0 3. Object Destructuring with Defaults function createUser ({ name , role = ' user ' , active = true , theme = ' light ' } = {}) { return { name , role , active , theme }; } // The = {} default allows calling with no arguments createUser (); // Works! createUser ({ name : ' Alice ' }); // { name: 'Alice', role: 'user', active: true, theme: 'light' } 4. Array Met