Recursion vs Iteration in JavaScript
When to use recursion vs iteration and the trade-offs.
Recursion vs Iteration
Recursion
function factorial(n) { if (n <= 1) return 1; return n * factorial(n - 1); }
Pros: clean, readable for tree/recursive problems. Cons: stack overflow for deep calls, overhead of function calls.
Iteration
function factorial(n) { let result = 1; for (let i = 2; i <= n; i++) result *= i; return result; }
Pros: no stack overflow, faster (no function call overhead). Cons: more verbose for tree problems.
When to Use Recursion
- Tree traversal (DOM, JSON, file systems).
- Divide-and-conquer (merge sort, quick sort).
- Problems with self-similar structure.
- When readability matters more than performance.
When to Use Iteration
- Simple loops (factorial, fibonacci with memoization).
- Deep recursion (stack overflow risk).
- Performance-critical code.
- When the iterative solution is equally readable.
The Takeaway
Recursion: clean for trees and self-similar problems, but risks stack overflow and has function call overhead. Iteration: no stack overflow, faster, but verbose for complex problems. Use recursion for trees and divide-and-conquer; iteration for simple loops and deep recursion.
Use recursion for tree traversal, divide-and-conquer, and self-similar problems (cleaner). Use iteration for simple loops, deep recursion (stack overflow risk), and performance-critical code (no function call overhead).
Yes. Each recursive call adds a frame to the call stack. For deep recursion (e.g., 10,000 calls), the stack overflows: RangeError: Maximum call stack size exceeded. Use iteration or tail call optimization (not supported in most JS engines).
Yes, slightly. Each recursive call has function call overhead (creating a new frame, managing the stack). For simple problems like factorial, iteration is faster. For complex problems like tree traversal, the readability benefit outweighs the small performance cost.
The ES6 spec includes it, but most engines (V8, SpiderMonkey) do not implement it. In practice, deep recursion still overflows the stack. Use iteration or trampolines for deep recursion in JS.
Yes. Any recursive function can be converted to iterative using an explicit stack (array). The iterative version avoids stack overflow but may be less readable. For simple recursion (factorial), iteration is straightforward. For complex recursion (tree traversal with backtracking), the iterative version is verbose.
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