•     let person = {};
      
      person.name = "John Doe";
      person.age = 20;

Array == Objects

Exemplo

•   let person = [];
    
    person.name = "John Doe";
    person["age"] = 20;
    person[0] = "Foo";
  
    console.log(person);

Output: ["Foo", name: 'John Doe', age: 20]

•   // ARRAY
    let [A, B] = [true, false];
    // OBJECT
    let {C, D} = {C: true, D: false};
    
    console.log(A) //! true;
    console.log(B) //! false;

Output: true, false

•     let soma = (num1, num2) => {
  
          return num1 + num2;
      }

•     globalvar = 1;
      
      OR
  
      window.globalvar = 1;