对IE8兼容的处理 password框的特殊处理 (placeholder属性)

   /** 对IE8兼容的处理 password框的特殊处理  对IE8兼容的处理
     * 1.建立一个text框
     * 2.获取焦点和失去焦点的时候切换
     */
    // 判断浏览器是否支持placeholder属性
    function isSupportPlaceholder() {
        var input = document.createElement('input');
        return 'placeholder' in input;
    }

    $(function() {
        if(!isSupportPlaceholder()) {
            $('input[type="password"]').each(
                    function() {
                        var pwdField = $(this);
                        var pwdVal = pwdField.attr('placeholder');
                        var pwdId = pwdField.attr('id');
                        // 重命名该input的id为原id后跟1
                        pwdField.after('<input id="' + pwdId +'1" type="text" style="color: darkgrey" value='+pwdVal+' autocomplete="off" />');
                        var pwdPlaceholder = $('#' + pwdId + '1');
                        pwdPlaceholder.show();
                        pwdField.hide();

                        pwdPlaceholder.focus(function(){
                            pwdPlaceholder.hide();
                            pwdField.show();
                            pwdField.focus();
                        });

                        pwdField.blur(function(){
                            if(pwdField.val() == '') {
                                pwdPlaceholder.show();
                                pwdField.hide();
                            }
                        });
                    }
            );
        }
    });