title: Check if two files contain a given string - Function error
body: <p>I'm making a function that will check if two files contain a given string. If both files DON'T contain the string, it should return undefined :(
  here is my code:</p>
  
  <pre><code>var fs = require("fs");
  
  function get_uniq(string, file1, file2, callback){
    fs.readFile(file1, 'utf8', function(err, data1) {
      if (err) throw err;
  
      i = data1.search(string);
      console.log(i);
      if(i == -1){
        fs.readFile(file2, 'utf8', function(err, data2) {
          if (err) throw err;
  
          j = data2.search(string);
          if(j == -1){
            return 1;
          }
          });
  
      }
  });
    callback();
  }
  var i = get_uniq("stringThatFilesDoesntContainin", "somefile.txt", "anotherfile.txt", function(){
  
  console.log(i);
  
  });
  </code></pre>
  
  <p>Any idea what the problem is?</p>