JS function to determine if two strings are anagrams

gistfile1.js

function check_anagrams(first_words, second_words) {
    
    if (first_words.length != second_words.length) {
        console.log(0);
        return;
    }
    var letters=[], is_anagram, first_word, second_word, exists;
     
    for (var i=0; i<first_words.length; i++) {

          first_word = first_words[i].split("");
          second_word = second_words[i].split("");

          if (first_words[i].length < 1 || second_words[i].length < 1) {
              console.log(1);
              continue;
          }
 
          letters = first_word.concat(second_word);
          letters = letters.sort();
          is_anagram = 1
          
          if (letters.length %2 !== 0) {
              is_anagram = 0
          }
          for (var j=0; j<letters.length-2; j+=2) {
              //console.log(letters[j]+" "+letters[j+1])
              if (letters[j]!=letters[j+1]) {
                  is_anagram = 0
              }
          }
         //console.log(letters+" "+is_anagram);
         
        //  second check  
        exists = []
        for (var f=0; f<first_word.length; f++) {
            exists[f]="no";
            for (var s=0; s<second_word.length; s++) {
                if (second_word[s] == first_word[f]) {
                    exists[f]="yes";
                    break;
                }
            };
        }
        //console.log(exists)
        
        if (exists.join("").indexOf("no") != -1) {
            console.log(0);
            continue;
        }
   
        //final 
        console.log(is_anagram);
          
    }
}