27.map，obj互转

var obj = {
  a: 1,
  b: 2,
  c: 3,
}

// obj转map
const res = new Map(Object.entries(obj))

// Map转obj
const res2 = {}
for (const [k, v] of res) {
  res2[k] = v
}
console.log('res,res2', res,res2)