如何选择课程

I have a problem, I tried to select CLOSEST to .search_box element with class .results using jQuery and show list from PHP.

$(".results").show().append(html)

This works bad, because list from PHP showed near all elements. I have few .calc_input_wrapper that are adding dynamicaly.

$(this).closest(".results").show().append(html)

This doesn't work.

<div class="calc_input_wrapper clearfix">
  <ul class="calc_input_list clearfix">
    <li class="product_number">1</li>
    <li class="product_input">
      <form method="post" action="do_search.php">
        <input  autocomplete="off" placeholder="Продукт" type="text" name="search" class='search_box'/>
      </form>
      <div class="delete_product_row"></div>
      <ul class="results" class="update">
      </ul>
    </li>
    <li class="product_weight">
      <form action="">
        <input autocomplete="off" type="text" placeholder="0">
      </form>
    </li>
    <li class="product_protein">-</li>
    <li class="product_fat">-</li>
    <li class="product_carboh">-</li>
    <li class="product_calor">-</li>
  </ul>
</div>

$(document).on('keyup', '.search_box', function() {
  // получаем то, что написал пользователь
  var searchString    = $(this).val();
  // формируем строку запроса
  var data = 'search=' + searchString;
  // если searchString не пустая
  if(searchString.length > 1) {
    // делаем ajax запрос
    $.ajax({
      type: "POST",
      url: "do_search.php",
      data: data,
      beforeSend: function(html) {
        $(".results").html('');
        $("#searchresults").show();
        $(".word").html(searchString);
      },
      success: function(html){
        //$(".results").show().append(html);                           
        console.log('omg');
      }
    });
  } else {
    $(".results").html('');
  }
  return false;
});

$(this) will not be same inside the ajax method' callback. Before the code which makes the call to $.ajax method, this represents the input box to which user entered some value. But inside the ajax method's success callback this represent the xhr object. So i suggest you keep the $(this) to a variable outside of your ajax call and use that.

Also you should use closest() method to get to the outer li element with css class "product_input" and use find() method to get the result div.

var _this = $(this);
$.ajax({
          //Your existing code
          success: function(html){
                _this.closest(".product_input").find(".results").show().html(html);       

          }
      });

Another option is to use the context property when making the ajax call. This will keep your this as it is. So you can simply use $(this) instead of the local variable.

$.ajax({
      //your existing code
       context: this,
       success: function (html) {
            $(this).closest(".product_input").find(".results").show().html(html);
      }
     });