We will change our theme’s function.php and header.php. If you don’t know about WordPress coding or PHP please don’t touch this files. If you wanna help send me e-mail about this function.

Here is the code;

First make a backup functions.php and header.php (These files under the your themes path [wp-content/theme/your-theme]). After backup, you can change this files and you can send them to your server.

Insert this code into theme’s Functions.php:

function hls_set_query() {
  $query  = attribute_escape(get_search_query());

  if(strlen($query) > 0){
    echo '
      <script type="text/javascript">
        var hls_query  = "'.$query.'";
      </script>
    ';
  }
}

function hls_init_jquery() {
  wp_enqueue_script('jquery');
}

add_action('init', 'hls_init_jquery');
add_action('wp_print_scripts', 'hls_set_query');

And after that, Open your theme’s header.php and paste this code before </head> tag.

<style type="text/css" media="screen">
    .hls { background: #D3E18A; }
  </style>
  <script type="text/javascript">
  jQuery.fn.extend({
    highlight: function(search, insensitive, hls_class){
      var regex = new RegExp("(<[^>]*>)|(\\b"+ search.replace(/([-.*+?^${}()|[\]\/\\])/g,"\\$1") +")", insensitive ? "ig" : "g");
      return this.html(this.html().replace(regex, function(a, b, c){
        return (a.charAt(0) == "<") ? a : "<strong class=\""+ hls_class +"\">" + c + "</strong>";
      }));
    }
  });
  jQuery(document).ready(function($){
    if(typeof(hls_query) != 'undefined'){
      $("#post-area").highlight(hls_query, 1, "hls");
    }
  });
  </script>

After that you can send files to your server. When you search you can see searched texts are highlighted!