add client validation for search form if it's input is null

application.js

  $('form[action*="search"]').live('submit', function(event) {
    event.preventDefault();
    arr_input = $('form').serializeArray();
    arr_input.shift();
    keywords_count = 0;
    $.map(arr_input, function(el){
     if(el.value != ""){keywords_count = keywords_count + 1} 
    });
    if(keywords_count <= 0){
      if($('.error.empty-search').length < 1){
        error_el = '<div class="alert-message error empty-search" style="display:none" data-alert="alert"><a class="close" href="#">×</a>Enter at least one search term to perform any search</div>'
        $('.breadcrumb').append(error_el)
        $('.error.empty-search').fadeIn('slow');
      }
    }else{
      $(this).attr({
        'data-pjax': '#content',
        'data-pjax-fragment': '#content' 
      });
      $('form').submit()
    }
  });