Question

How to print characters that have even frequencies of occurrence in a string with JavaScript

Answer 1

var isLetter = function(ch){
   return ch.length === 1 && ch.match(/[a-z]/i);
}

function print_even_frequencies_char(s) { 
    var letters = new Array(256).fill(0);
    
    for (var i = 0; i < s.length; i++) {
         if (isLetter(s[i])) {
             letters[s[i].charCodeAt(0)]++;
         }
    }
            
    for (var i = 0; i < 256; i++) { 
         if (letters[i] !== 0 && letters[i] % 2 === 0) {
             document.write(String.fromCharCode(i) + " " + letters[i] + "<br />");
         }
    } 
} 



var s = "javascript programming pro OO"; 

print_even_frequencies_char(s);


    
    
/*
run:
     
O 2
g 2
i 2
m 2
o 2
r 4
     
*/

 

70+ SQL courses for beginners and professionals