Deep Dive: Array Internals & Memory Layout

Array Internals & Memory Layout WHAT YOU'LL LEARN Arrays store elements in contiguous memory blocks — each element sits right next to the previous one Random access is O(1) because the address of arr[i] is just baseAddress + i * elementSize — a single arithmetic operation Insertion/deletion at arbitrary positions is O(n) because elements must be shifted to maintain contiguity JavaScript arrays are actually hash maps under the hood for sparse arrays, but V8 optimizes dense arrays to use contiguous backing stores Why it matters: Understanding the memory model explains WHY array operations have the complexities they do, rather than memorizing a table. It also informs when to choose arrays vs. linked lists or hash maps. Contiguous Memory & O(1) Access In a true array, elements are packed sequentially in memory. To read arr[i], the CPU computes baseAddress + i * sizeof(element) and jumps directly there — no traversal needed. This is why arrays have O(1) random access while linked li