Proving Your JavaScript Seniority in 2026 The bar for senior frontend interviews has risen dramatically. Whether you're targeting a Senior Frontend Engineer role at Google in Mountain View, a Staff Engineer position at Spotify in Stockholm, or a Lead Developer role at Shopee in Singapore — modern frontend interviews require moving far past traditional scope and hoisting questions. You need to demonstrate architectural prowess , deep runtime understanding , and production-grade patterns in modern ECMAScript. This guide covers the 10 essential JavaScript patterns that separate senior candidates from mid-level ones in 2026. For each pattern, we explain what it is , why interviewers ask it , how to implement it , and where it appears in real-world frameworks . 1. The Advanced Closure (Memoization & Private State) What it is: Use closures not just to hide variables, but to cache heavy computations and create truly private state.…