How to find frequency of each character in a string using js?

Question

function problem14(){
    var count=0;
    var input1 = document.getElementById('input14').value;
    for(var i=0; i<input1.length; i++){
        for(var j=0; j<input1.length; j++){
            if(input1.charAt(i)==input1.charAt(j)){
                //What to Write Here ? 
                //If I do Write So far
            }
        }
    }
    document.getElementById('problem14').innerHTML = count;
}

Plz Help Guyss What to Write ... Where I Use Comments..

Does this answer your question? [Count number of occurrences for each char in a string](https://stackoverflow.com/questions/19480916/count-number-of-occurrences-for-each-char-in-a-string) — Peter Pajchl, Mar 09 '21 at 17:11
Input1 has a String ... It depends what ever a User write there... this String Stores in input1 variable — talha habib, Mar 09 '21 at 17:12

54ka · Answer 1 · 2021-03-09T18:13:43.107

Get string and split to array
Loop array and add values from array in key in object. If a key with this value has already been created, +1 will be added as the value of this key.

I hope this code works for you.

Example with forEach:

function counter(par) {
    var spar = par.split('');
    var cnt = {};
    spar.forEach(function (x) { 
        cnt[x] = (cnt[x] || 0) + 1; 
    });
    return cnt;
}

console.log(counter("aabsfgssdfg"));

Example with for of:

function counter(par) {
    var spar = par.split('');
    var cnt = {};
    for (var i of spar) {
        cnt[i] = (cnt[i] || 0) + 1;
    }
    return cnt;
}

console.log(counter("aabsfgssdfg"));

score 0 · Answer 2 · answered Mar 09 '21 at 17:19

basically what you need to do is to have an object where to store the additions of each letter, after that you can compare if you already have it then you add 1, if there is no entry for that, you start with 1.

take a look to the comments, you will see how it works

function problem14() {
  // to hold all the letter repetitions
  const letters = {};

  // to get the value that the user enters
  let input1 = document.getElementById('input14').value;

  // loop over the input text
  for (let i = 0; i < input1.length; i++) {
    // save the letter that we are looking
    let currentLetter = input1[i];

    // lets compare, if the current letter is already counted we add 1
    if (letters[currentLetter]) {
      letters[currentLetter] += 1;
    } else {
      // this means the letter was not in our object, so we initialize it using 1
      letters[currentLetter] = 1;
    }
  }

  // the JSON.stringify function is just to show it in a readable way
  document.getElementById('result').innerHTML = JSON.stringify(letters, null, 4);
}


document.getElementById("button").addEventListener("click", function() {
  problem14();
});

<input id="input14">
</br>
<button id="button"> count </button> 
</br>
result: <label id="result"></label>

the problem with yours @talhahabib is that you are trying to keep the counts in only 1 variable (count) and you won't get the count of each character — Prince Hernandez, Mar 09 '21 at 17:57
hmm yeah... But i can't find the easy way. Your code is Right but some lines I can't understand — talha habib, Mar 10 '21 at 03:09
which one? that is why I added the comments so you can read them and understand the logic — Prince Hernandez, Mar 10 '21 at 20:19

score 0 · Answer 3 · answered Mar 09 '21 at 17:19

function problem14(){
var count=0;
var input1 = document.getElementById('input14').value;
var hashTable = {}
for (var i= 0 ; i < input1.length; i++) {
    if (hashTable[input1[i]]) {
         hashTable[input1[i]] += 1
    } else {
        hashTable[input1[i]] = 1
    }
  }
}

hashTable object will contain the charaters and their count

How to find frequency of each character in a string using js?

3 Answers3