placeholder兼容ie

//判断浏览器是否支持 placeholder属性
    function isPlaceholder(){
        var input = document.createElement('input');
        return 'placeholder' in input;
    }
    if (!isPlaceholder()) {//不支持placeholder 用jquery来完成
        if(!isPlaceholder()){

                $("input").not("input[type='password']").focus(function() {
                    var input = $(this);
                    if (input.val() == input.attr("placeholder")) {
                        input.val("");
                        input.removeClass("placeholder");
                    }
                }).blur(function() {
                    var input = $(this);
                    if (input.val() == "" || input.val() == input.attr("placeholder")) {
                        input.addClass("placeholder");
                        input.val(input.attr("placeholder"));
                    }
                }).blur().parents("form").submit(function() {
                    $(this).find("[placeholder]").each(function() {
                        var input = $(this);
                        if (input.val() == input.attr("placeholder")) {
                            input.val("");
                        }
                    });
                });
                //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    = $(".passShow");
                var pwdVal      = pwdField.attr('placeholder');
                pwdField.after('<input id="pwdPlaceholder" class="passtxt" type="text" 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();
                    }
                });
                
            }
    }