Deep Dive into Array.reduce(): From Interview Questions to Design Thinking

While preparing for frontend interviews, I noticed an interesting phenomenon: many problems I encountered could be elegantly solved using reduce , yet when I looked back at my actual project experience, I had rarely used it directly. This gap between "interview frequency" and "project rarity" made me reconsider this array method—is it just syntactic sugar, or does it represent a deeper programming paradigm? This article documents my journey of relearning reduce . I want to explore not just "how to use it," but "why use it" and "when to think of it." Why Revisit Array.reduce() The Interview vs. Reality Paradox Looking through LeetCode and various interview problem sets, reduce is everywhere: Summing or multiplying array values Flattening arrays Implementing map and filter Function composition (compose/pipe) Object transformation and grouping But in actual projects, I've been more comfortable using for loops, map , filter , or even forEach . Why is that? My reflection: perhaps it's not t