计算字符串中每个字符的出现次数，并将其放入数组中

function countCharacters(str) {
  const charCount = {}; // 哈希表，用于记录字符和出现次数的对应关系

  // 遍历字符串的每个字符
  for (let i = 0; i < str.length; i++) {
    const char = str[i];

    // 如果字符已经在哈希表中存在，将对应的出现次数加1
    if (charCount[char]) {
      charCount[char]++;
    } else {
      // 如果字符不在哈希表中，将字符作为键，初始出现次数为1作为值，添加到哈希表中
      charCount[char] = 1;
    }
  }

  const result = [];

  // 遍历哈希表，将每个字符和对应的出现次数放入数组中
  for (const char in charCount) {
    result.push({
      character: char,
      count: charCount[char]
    });
  }

  return result;
}

const str = "Hello, World!";
const charCounts = countCharacters(str);
console.log(charCounts);

[
  { character: 'H', count: 1 },
  { character: 'e', count: 1 },
  { character: 'l', count: 3 },
  { character: 'o', count: 2 },
  { character: ',', count: 1 },
  { character: ' ', count: 1 },
  { character: 'W', count: 1 },
  { character: 'r', count: 1 },
  { character: 'd', count: 1 },
  { character: '!', count: 1 }
]