Html5/Css3 向下兼容placeholder

//@charset "utf-8";

/**

 * jquery版本要求：1.3 ~ 1.8，HTML声明请遵循W3C标准

 * 用来处理placeholder的插件

 * 兼容IE6浏览器

 * @author [e-mail]

 * @version 1.0

 * @date 2013-4-15 11:16:59

 */

function isPlaceholder() {

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

    return 'placeholder' in input;

}

if (!isPlaceholder()) {//不支持placeholder 用jquery来完成 

    $(document).ready(function () {

        if (!isPlaceholder()) {

            $("input").not("input[type='password']").each(//把input绑定事件 排除password框 

                function () {

                    if ($(this).val() == "" && $(this).attr("placeholder") != "") {

                        $(this).val($(this).attr("placeholder"));

                        $(this).focus(function () {

                            if ($(this).val() == $(this).attr("placeholder")) $(this).val("");

                        });

                        $(this).blur(function () {

                            if ($(this).val() == "") $(this).val($(this).attr("placeholder"));

                        });

                    }

                });

            //对password框的特殊处理1.创建一个text框 2获取焦点和失去焦点的时候切换 

            var pwdField = $("input[type=password]");

            var pwdVal = pwdField.attr('placeholder');

            pwdField.after('<input id="pwdPlaceholder" type="text" class="btn_login2" value=' + pwdVal + ' autocomplete="off" />');

            var pwdPlaceholder = $('#pwdPlaceholder');

            pwdPlaceholder.show();

            pwdField.hide();

            pwdPlaceholder.focus(function () {

                pwdPlaceholder.hide();

                pwdField.show();

                pwdField.focus();

            });

            pwdField.blur(function () {

                if (pwdField.val() == '') {

                    pwdPlaceholder.show();

                    pwdField.hide();

                }

            });

        }

    });

}