如何使用具有向后兼容性的HTML5占位符属性？

<!--[if lt IE 10]><script>
  document.createElement('input').placeholder || (function () {
    var nodes = document.getElementsByTagName('input');
    for (var i = 0; i< nodes.length; i++) {
      var item = nodes[i],
          txt = item.getAttribute('placeholder');
      if (txt) {
        if (item.value === '') {
          item.value = txt;
          item.style.color = '#aaa';
        }
        item.onfocus = function () {
          if (this.value === this.getAttribute('placeholder')) {
            this.value = '';
            this.style.color = '#000';
          }
        };
        item.onblur = function () {
          if (this.value === '') {
            this.value = this.getAttribute('placeholder');
            this.style.color = '#aaa';
          }
        };
      }
    }
  })();
</script>
<![endif]-->

  $(function () {
    $('input, textarea').placeholder();
  });
</script>