Detailed explanation of the usage methods of set collection and map collection in ES6 and source code examples

//Create a set collection and pass the argument into an iterable objectconst s1 = new Set(iterable);

// () Add data to the created collection    const s1 = new Set();
    (1)
    (2)
    (3)
    (4)
    (1) //Invalid addition because the data is duplicated    (s1)

// () Determine whether the data exists    ((1))
    ((10))

// () Return whether the deletion is successful    (1)
    (s1)
    ((10))

// () Clear the collection    ()
    (s1)

// Properties can only be read, not modified    ()

// 6.Travel: for of, because it is an iterable object    for(const item of s1){
        (item)
    }
    // Rewrite instance method forEach    ((item, index, s) => {
        // index is not a subscript, the set collection has no subscript        // The value of the first parameter in forEach is the same and the value of the second parameter, both representing each item of data in set        (item, index, s)
    })

//Deduplication of array  const arr = [1,1,22,22,3,1,88,88,65,123,444,65];
  const s = new Set(arr);
  ([...s]);

//Or it will be done in one sentence  const result = [...new Set(arr)];
  (result);//[1,22,3,88,65,123,444,65]

// The intersection, union, difference of two arrays, and the result is a new array  const arr1 = [12,34,55,33,11,33,5,12];
  const arr2 = [55,34,11,78,10,19,88,88,99,99];

// Complete with set// Intersection: You have array elements that I have, and form a new array  const cross = [...new Set(arr1)].filter(item => (item) >= 0);
  (cross);//[]

// Unity: New array after combining and deduplication  const result = [...new Set([...arr1,...arr2])];
  (result);

// Difference set: You have and I don't, I have array elements that you don't. Make up a new array  let arr4 = (item=>{
      // judging the data that exists in arr1 and does not exist in arr2 and data that does not exist in arr1 and does not exist in arr2      return (item) && !(item) || !(item) && (item)
  })
  (arr4)  //[12, 33, 5, 78, 10, 19, 88, 99]

let swk=new Map()
(swk);//Map(0)

        let swk=new Map();
         (swk);      

    // 1. Add map element        // (key,value) Set the key-value pair of Map object (key name, key value) Return to the current object        ('uname', 'Sun Wukong');
        ('age', 600);
        ('master', 'Tang Monk');
        ('weapon', 'Golden Cudgel');
        (swk); //Map(4) {'uname' => 'Sun Wukong', 'age' => 600, 'master' => 'Tang Monk', 'weapon' => 'Golden Cudgel'}        ('age', 601);
        (swk);
        // If the key does not exist, add an item        // If the key exists, modify it
   // 2. Get map element        // (key) Returns the value corresponding to the key value. If the key does not exist, it returns undefined        (('uname')); //Sun Wukong        (({})); //undefined

   // 3. Determine whether the element exists has Return a boolean value        (('uname')); //true
        (({})); //false

  // 4. Delete the map element        ('weapon');
        (swk); //Map(3) {'uname' => 'Sun Wukong', 'age' => 600, 'master' => 'Tang Monk'}
  //5. Clear the map elements        // ();
        // (swk); //Map(0) {size: 0}

  // 6. Map element length        (); //3

  // 7. You can use the for of loop        for (let [key, value] of swk) {
            (key, value);
            for (let item in value) {
                (value[item])
            }
        }

        ('=====forEach=====');


  // 8. You can use forEach to traverse        ((item, index, map) => {
            (index); //uname age master
            ('==========');
            (item); // Sun Wukong 60 Monk Tang            ('==========');
            (map);
            ('==========');
        })