Pure Functions & Side Effects

A pure function always returns the same output for the same input and has no side effects — it doesn't modify anything outside itself.

// Pure — no side effects
function add(a, b) { return a + b; }

// Impure — modifies external state
let total = 0;
function addToTotal(n) { total += n; } // side effect!

Pure functions are easier to test, debug, and reason about. Strive for them when possible.

FINAL CHALLENGE

Write a pure function clamp that takes a number, a min, and a max. It should return the number clamped within that range. Test it with clamp(15, 0, 10) and print the result.

Need a hint?

Use Math.min(max, Math.max(min, n)) or an if/else chain.

Expected Output:

10