(function($) {

  /**

   * 牛叉的解决方案

   */

  var placeholderfriend = {

    focus: function(s) {

      s = $(s).hide().prev().show().focus();

      var idValue = s.attr("id");

      if (idValue) {

        s.attr("id", idValue.replace("placeholderfriend", ""));

      }

      var clsValue = s.attr("class");

      if (clsValue) {

        s.attr("class", clsValue.replace("placeholderfriend", ""));

      }

    }

  }

  //判断是否支持placeholder

  function isPlaceholer() {

    var input = document.createElement('input');

    return "placeholder" in input;

  }

  //不支持的代码

  if (!isPlaceholer()) {

    $(function() {

      var form = $(this);

      var elements = form.find("input[type='text'][placeholder]");

      elements.each(function() {

        var s = $(this);

        var pValue = s.attr("placeholder");

        var sValue = s.val();

        if (pValue) {

          if (sValue == '') {

            s.val(pValue);

          }

        }

      });

      elements.focus(function() {

        var s = $(this);

        var pValue = s.attr("placeholder");

        var sValue = s.val();

        if (sValue && pValue) {

          if (sValue == pValue) {

            s.val('');

          }

        }

      });

      elements.blur(function() {

        var s = $(this);

        var pValue = s.attr("placeholder");

        var sValue = s.val();

        if (!sValue) {

          s.val(pValue);

        }

      });

      var elementsPass = form.find("input[type='password'][placeholder]");

      elementsPass.each(function(i) {

        var s = $(this);

        var pValue = s.attr("placeholder");

        var sValue = s.val();

        if (pValue) {

          if (sValue == '') {

            var html = this.outerHTML || "";

            html = html.replace(/\s*type=(['"])?password\1/gi, " type=text placeholderfriend").replace(/\s*(?:value|on[a-z]+|name)(=(['"])?\S*\1)?/gi, " ").replace(/\s*placeholderfriend/, " placeholderfriend value='" + pValue + "' " + "onfocus='placeholderfriendfocus(this);' ");

            var idValue = s.attr("id");

            if (idValue) {

              s.attr("id", idValue + "placeholderfriend");

            }

            var clsValue = s.attr("class");

            if (clsValue) {

              s.attr("class", clsValue + "placeholderfriend");

            }

            s.hide();

            s.after(html);

          }

        }

      });

      elementsPass.blur(function() {

        var s = $(this);

        var sValue = s.val();

        if (sValue == '') {

          var idValue = s.attr("id");

          if (idValue) {

            s.attr("id", idValue + "placeholderfriend");

          }

          var clsValue = s.attr("class");

          if (clsValue) {

            s.attr("class", clsValue + "placeholderfriend");

          }

          s.hide().next().show();

        }

      });

    });

  }

  window.placeholderfriendfocus = placeholderfriend.focus;

})(jQuery);

<script src="Content/jquery/dist/placeholderfriend.js"></script>