text: const dogs = new Map();//对象集合 
  dogs.set('Snickers',3);
  dogs.set('Sunny',2);
  dogs.set('Hugo',10);
  dogs.set('Hugo',11);
  
  dogs.forEach((val,key) => console.log(val,key));
  
  
  // 可以迭代的都可以使用for of
  for( const [key,val] of dogs) {
      console.log(key,val);
  }
  
  let a =1;
  let b =2;
  //解构
  [a,b] = [b,a];
  console.log(a,b);