JavaScript |返回字符串中最常见的多个字符

Question

所以我正在学习如何返回字符串中最常见的字符。我知道如果只有一个字符出现最多，即“javascript”中的“a”出现两次，其余字符仅出现一次，我知道该怎么做。但如果字符串是“javascript prototype”，则有两个字符出现最多，即“p”和“t”。我正在使用 _.invert() 来获取字母出现次数最多的数字的值，但由于“p”和“t”都等于 3，所以我可以返回它们。我预计输出是 “pt”

// Return the character that is most common in a string
// ex. maxCharacter('javascript') == 'a'
// Return multiple characters that are most common in a string
// ex. maxCharacter('javascript prototype') == 'p t'
function maxCharacter(str) {


  const charMap = {};
  let maxNum = 0;
  let maxChar = '';

  str.replace(/\s/gi, '').split('').forEach(function(char){
    if(charMap[char]){
      charMap[char]++;
    } else {
      charMap[char] = 1;
    }
  });
  

  for(let char in charMap){
    if(charMap[char] > maxNum) {
      maxNum = charMap[char];
      maxChar = (_.invert(charMap))[maxNum];
    }
  }
  return maxChar;
}



// Call Function
const output = maxCharacter('javascript prototype');

console.log(output);

Answer 1

通过 spreading 查找 charMap 中的最大数字Object.values()进入Math.max() 。然后使用Array.filter()仅获取具有最大值的键，并用空格将它们连接起来:

function maxCharacter(str) {
  const charMap = {};

  str.replace(/\s/gi, '').split('').forEach(function(char){
    if(charMap[char]){
      charMap[char]++;
    } else {
      charMap[char] = 1;
    }
  });
  
  const max = Math.max(...Object.values(charMap));
  
  return Object.keys(charMap)
    .filter((c) => charMap[c] === max)
    .join(' ');
}

console.log(maxCharacter('javascript')); // a
console.log(maxCharacter('javascript prototype')); // p t