Clean Code - IF Statements

index.ts

// See [basarat] (https://github.com/basarat/demo-guard-clauses)
class Person {
  age?: number;
  experience?: number;
}

// demo-guard-clauses
function update(button: number, person: Person | null) {
  if (button !== 1 || !person) { return; }
  if (person.age == null) { throw new Error('Person age not set'); }
  if (person.experience == null) { throw new Error('Person experience not set'); }

  person.experience += 10;
  person.age++;
}