JavaScript | Returning multiple characters that is most common in a string

Question

So I am learning how to return the most common character in a string. I know how to do it if there is only one character that appears the most-e.i, the "a" in "javascript" which appears twice and the rest of the characters appear only once. But if the string is 'javascript prototype', there are two characters that appear the most which are "p" and "t". I am using the _.invert() to get the value of the number in which letters appear the most and I though since "p" and "t" both equal 3 then I could return them. I expected the output to be "p t"

// 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);

Ori Drori · Accepted Answer · 2018-04-30 18:22:37Z

2

Find the max number in the charMap by spreading the Object.values() into Math.max(). Then use Array.filter() to get just the keys that have the max value, and join them with a space:

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

answered Apr 30, 2018 at 18:22

Ori Drori

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