01_variables.test.js

describe("About variables", () => {
  it('should understand VAR', () => {
    var x = 5;
    var x = 6;
    expect(x).toBe(5);
  });

  it('should understand the difference of LET and VAR', () => {
    var x = 6;
    let x = 5;
    expect(x).toBe(5);
  });

  it('should understand LET', () => {
    let x = 5;
    let x = 6;
    expect(x).toBe(6);
  });

  it('should understand LET scoping', () => {
    let x = 5;

    function foo() {
      let x = 20;

      return x;
    }

    expect(x).toBe(20);
  });

  it('should understand CONST - scalar values', () => {
    const x = 5;
    x = 'foo';
    expect(x).toBe(5);
  });

  it('should understand CONST - assignment', () => {
    const x;
    x = 5
    expect(x).toBe(5);
  });

  it('should understand CONST - objects', () => {
    const person = {
      "name": "Linus",
      "age": 42
    };

    expect(person.lastname).toBe('torvalds');
  });
});