JSFiddle - React, Tailwind, and code Playground

JavaScript

var firstString = "hello world 32";
    var secondString = "FOLLOW me 231";
    var firstChars = [];
    var secondChars = [];
    var arrLength = 122; 
    // 0 - 122 covers ASCII values for all chars a-z (lowers), A-Z (uppers), numbers, and empty spaces.
      
    //initialize array to arrLength number of elements, all set to 0.
    for (var i = 0; i < arrLength; i++)
    {
        firstChars.push(0);
        secondChars.push(0);
    }
    
    //count first word chars
    for (var i = 0; i < firstString.length; i++)
        firstChars[firstString.charCodeAt(i)]++;
    
    //count second word chars
    for (var i = 0; i < secondString.length; i++)
        secondChars[secondString.charCodeAt(i)]++;
  
    //output matching chars and the count of occurences.
    for (var i = 0; i < arrLength; i++)
    {
        if (firstChars[i] > 0 && secondChars[i] > 0)
        {
            var letter = i == 32? "Empty Space" : String.fromCharCode(i);
            var count = firstChars[i] + secondChars[i];
          
            console.log(letter + " : " + count);
        }
    }