出一道有难度的js编程题并给出答案

题目：写一个函数，接收一个字符串作为参数，返回该字符串中出现次数最多的字符及其出现次数。如果有多个字符出现次数相同，则返回其中ASCII码最小的那个字符。

答案：

function getMaxChar(str) { let map = new Map(); let maxCount = 0; let maxChar = ''; for (let i = 0; i < str.length; i++) { let char = str[i]; let count = map.get(char); if (!count) { count = 0; } count++; map.set(char, count); if (count > maxCount) { maxCount = count; maxChar = char; } else if (count === maxCount && char.charCodeAt(0) < maxChar.charCodeAt(0)) { maxChar = char; } } return { char: maxChar, count: maxCount }; }

console.log(getMaxChar('abcaabc')); // {char: 'a', count: 3}