interface ISort {
  name: string,
  age: number
}

function sortByName(a: ISort[]) {
  var result = a.slice(0);
  result.sort((x, y) => {
    return x.name.localCompare(y.name);
  });
  return result;
}

error TS2339: Property 'localCompare' does not exist on type 'string'.

function countLines(text?: string[]): number {
  let count = 0;
  for (const line of text) {
    if (line && line.length !== 0) {
      count = count + 1;
    }
  }
  return count;
}

error TS2532: Object is possibly 'undefined'.

class Person {
  protected name: string;
  public age: number;
  constructor(name: string) { this.name = name; }
}

class Employee extends Person {
  static someAttr = 1;
  private department: string;

  constructor(name: string, department: string) {
    super(name);
    this.department = department;
  }
}
let howard = new Employee("Howard", "Sales");
console.log(howard.name);

error TS2445: Property 'name' is protected and only accessible within class 'Person' and its subclasses.

interface Machine {
  move(): void
}

interface Human {
  run(): void
}

class Robot implements Machine, Human {
  run() {
    console.log('run');
  }
}

error TS2420: Class 'Robot' incorrectly implements interface 'Machine'.
  Property 'move' is missing in type 'Robot'.