text: 
  const obj = {
    "key1": 1,
    2: "value 2",
    key3: 3,
    null: "value for null",
    undefined: 5,
    objectKey: {
      1: 1,
      2: 2
    }
  }
  
  obj["key3"] = "testing"
  console.log(obj["key3"])
  
  
  const obj = {0: "first", 1: "second", 2: "third"}
  obj[0]
  obj[0] = "New first"
  console.log(obj)
  
  
  typeof [1, 2, 3]
  
  
  const obj = {1: "a", 2: "b", 3: "c"}
  console.log(obj)
  console.log("keys: ", Object.keys(obj))
  console.log("values: ", Object.values(obj))
  
  
  obj[1] = null
  console.log(obj)
  delete obj[1]
  console.log(obj)
  
  
  
  
  
  
  
  