代码块 -- diff

问题 & 解答 非原创

Q: 写一个diff方法, 用于比较两个数组, 返回两数组中不同的部分; 要求考虑算法性能, 使用es6/es7语法, 不能使用第三方类库

console.log(diff([1, 2], [2, 1]));  // => []
console.log(diff([1, 2, 1], [2, 1, 1, 2]));  // => []
console.log(diff([1, 2, 3], [4, 3, 1]));   // => [2, 4]
console.log(diff([1, [2, 3], 4], [[1 ,2], [2, 3], 3, 4]));  // => [1, [1, 2], 3]
console.log(diff([[1, 2, 3], [3, 2, 1], 1, 2, 3], [2, 3, 1]));   // => [[1, 2, 3], [3, 2, 1]]

• 代码

  function diff(a = [], b = []) {
      a = Array.from(new Set(a));
      b = Array.from(new Set(b));
      const arr = a.concat(b);
      const m = new Map();
      arr.map((item) => {
          const itemJson = JSON.stringify(item);
          if (!m.has(itemJson)) m.set(itemJson, item);
          else m.delete(itemJson);
      });
      return Array.from(m.values());
  }
  
  console.log(diff([1, 2], [2, 1]));  // => []
  console.log(diff([1, 2, 1], [2, 1, 1, 2]));  // => []
  console.log(diff([1, 2, 3], [4, 3, 1]));   // => [2, 4]
  console.log(diff([1, [2, 3], 4], [[1 ,2], [2, 3], 3, 4]));  // => [1, [1, 2], 3]
  console.log(diff([[1, 2, 3], [3, 2, 1], 1, 2, 3], [2, 3, 1]));   // => [[1, 2, 3], [3, 2, 1]]