code: function filterTitle(posts) {
        var reTitle = title.map(function makeRE(word) {
          return new RegExp(word, 'i');
        });
  
        return posts.filter(function filterPosts(post) {
          return reTitle.every(function checkRE(regex) {
            return regex.test(post.title) || regex.test(post.slug);
          });
        });
      }
docs: filter the posts with the supplied regular expression