etTimeout(function() {
            var element = document.getElementById("wait-add-class-target");
            element.classList.add("new-one");
            }, 3000);
            }
        </script>
        <button id="wait-add-class-trigger" onclick="button_add_class()">Test</button>
        <span id="wait-add-class-target" class="some-old another-old"></span>

        <h3>Element location section</h3>
        <input type="text" id="el-location-input"></input>

        <h3>Active element section</h3>
     