二维数组中找到出现多次的元素

Question

var arr=new Array(["A","B"],["C","D"],["E","F"],["A","C"],["D","F"],["E","A"],["A","F"]);var output_arr=new Array();//找出出现过三次及以上的元素,写入到output_arr这个一维数组中//"A"出现了4次，"F"出现了3次output_arr = ["A","F"];

Answer 1

给你个参考- -

let arr = new Array(["A", "B"], ["C", "D"], ["E", "F"], ["A", "C"], ["D", "F"], ["E", "A"], ["A", "F"]);

let result = [],list = {},output_arr = [];

计算元素出现次数并筛选出符合条件的元素

  for (let [val1, val2] of arr) {

    result.push(val1, val2);

  }

  for (let val of result) {

    list[val] ? list[val] += 1 : list[val] = 1;

    if (list[val] === 3) { //出现3次以上的元素

      output_arr.push(val); //装进数组

    }

  }

查看结果

  console.log(output_arr);