JavaScript implements a method for the default display of the background image in the text box to disappear after gaining focus

<p class="contain">
    <p class="inputFullNameContain"><input class="inputFullName" type="text" id="search_content" /> </p>
    </p>

 <script type="text/javascript" >
     (function () {
         var id = document.getElementById('search_content');
         if (id) {
             var name = id;
             var unclicked = function () {
                 if (name.value == '') {
                     name.style.background = 'url("images/inputBackground.png") no-repeat center';
                 }
             };
             var clicked = function () {
                 name.style.background = 'none';
             };
             name.onfocus = clicked;
             name.onblur = unclicked;
             unclicked();
         }
     })();
</script>