js字符串字符出现最大次数并统计次数的三种方法

第一种

const fun = (str) => {
  let map = new Map();
  let maxValue = "";
  let maxNum = 0;
  for (let item of str) {
    map.set(item, (map.get(item) || 0) + 1);
  }
  for (let [key, value] of map) {
    if (value > maxNum) {
      maxValue = key;
      maxNum = value;
    }
  }
  return [maxValue, maxNum];
};
console.log(fun("abcabcabccc"));

第二种

const fun = (str) => {
  let obj = {};
  let maxValue = "";
  let maxNum = 0;
  for (let key of str) {
    obj[key] = !obj[key] ? 1 : obj[key] + 1;
  }
  for (let key in obj) {
    if (obj[key] > maxNum) {
      maxValue = key;
      maxNum = obj[key];
    }
  }
  return [maxValue, maxNum];
};
console.log(fun("abcabcabccc"));

第三种

const fun = (str) => {
  //出现次数字符最多
  let maxValue = "";
  //出现次数字符最多的数字
  let maxNum = 0;
  //排序
  str = str.split("").sort().join("");
  //正则匹配
  let reg = /(\w)\1+/g;
  str.replace(reg, (val, item) => {
    if (val.length > maxNum) {
      maxNum = val.length;
      maxValue = item;
    }
  });
  console.log(str.match(reg));
  return [maxValue, maxNum];
};
console.log(fun("abcabcabccc"));