Explain control flow analysis and type narrowing in TypeScript.

TypeScript analyzes code flow to narrow types based on conditions, assignments, and type guards. Type Narrowing with typeof: function padLeft(padding: number | string, input: string): string { if (typeof padding === 'number') { // TypeScript knows padding is number here return new Array(padding + 1).join(' ') + input; } // TypeScript knows padding is string here return padding + input; } Truthiness Narrowing: function getUserName(user: { name?: string }) { if (user.name) { // TypeScript knows user.name is string (not undefined) return user.name.toUpperCase(); } return 'Anonymous'; } Discriminated Unions: type Shape = | { kind: 'circle'; radius: number } | { kind: 'square'; sideLength: number }; function getArea(shape: Shape) { switch (shape.kind) { case 'circle': // TypeScript knows shape has radius property return Math.PI * shape.radius ** 2; case 'square': // TypeScript knows shape has sideLength property return shape.sideLength ** 2; } } Custom Type Guards: function isString(value: unknown): value is string { return typeof value === 'string'; } function processValue(value: unknown) { if (isString(value)) { // TypeScript knows value is string console.log(value.toUpperCase()); } } Benefits: • Eliminates need for type assertions • Provides compile-time safety • Enables precise type checking • Improves code reliability.