一、 利用Set

    • new Set
    • filter

    • has

      1. let a = new Set([1, 2, 3]);
      2. let b = new Set([4, 3, 2]);
      3. //并集
      4. let union = [...new Set([...a],[...b])];
      5. // Set {1, 2, 3, 4}
      6. //  [1,2,3,4]
      7. //交集
      8. let intersect = new Set([...a].filter(x=> b.has(x)))
      9. // set {2, 3}
      10. // [2,3]
      11. //差集
      12. // （a 相对于 b 的）差集
      13. let difference = new Set([...a].filter(x => !b.has(x)));
      14. // Set {1}
      15. // [1]

      二、利用数组的方法

    • [].includes

    • filter ```javascript let a = [1, 2, 3]; let b = [2, 4, 5];

    // 并集 let union = a.concat(b.filter(v => !a.includes(v))) // [1,2,3,4,5]

    // 交集 let intersection = a.filter(v => b.includes(v)) // [2]

    // 差集 let difference = a.concat(b).filter(v => !a.includes(v) || !b.includes(v)) // [1,3,4,5] ```