Practical Immutability in TypeScript

Why Immutability Helps

// Bug: shared state causes unexpected behavior
const filters = { active: true, category: 'all' };
const savedFilters = filters; // Not a copy!
filters.active = false;
console.log(savedFilters.active); // false - oops!

// Fix: immutable update creates a new object
const filters2 = { active: true, category: 'all' };
const savedFilters2 = { ...filters2 }; // Actual copy
filters2.active = false;
console.log(savedFilters2.active); // true - safe!