asp.net – 访问offsetParent时是否存在IE 6/7“未指定错误”错

发布时间：2020-12-16 04:08:54 所属栏目：asp.Net 来源：网络整理

导读：我在一个简单的ASP.NET概念验证应用程序中使用jQuery UI的可拖动和可放置库.此页面使用ASP.NET AJAX UpdatePanel进行部分页面更新.该页面允许用户将项目放入垃圾桶div,它将调用从数据库中删除记录的回发,然后重新绑定该项目为药物的列表(以及其他控件).所有

我在一个简单的ASP.NET概念验证应用程序中使用jQuery UI的可拖动和可放置库.此页面使用ASP.NET AJAX UpdatePanel进行部分页面更新.该页面允许用户将项目放入垃圾桶div,它将调用从数据库中删除记录的回发,然后重新绑定该项目为药物的列表(以及其他控件).所有这些元素(可拖动项和垃圾桶div)都在ASP.NET UpdatePanel中.

这是拖放初始化脚本：

function initDragging()
    {
        $(".person").draggable({helper:'clone'});
        $("#trashcan").droppable({
            accept: '.person',tolerance: 'pointer',hoverClass: 'trashcan-hover',activeClass: 'trashcan-active',drop: onTrashCanned
        });
    }

    $(document).ready(function(){
        initDragging();

        var prm = Sys.WebForms.PageRequestManager.getInstance();
        prm.add_endRequest(function()
        {
            initDragging();
        });
    });

    function onTrashCanned(e,ui)
    {
        var id = $('input[id$=hidID]',ui.draggable).val();
        if (id != undefined)
        {
            $('#hidTrashcanID').val(id);
            __doPostBack('btnTrashcan','');
        }

    }

当页面回发,部分更新UpdatePanel的内容时,我重新绑定了draggables和droppables.当我用光标抓住一个draggable时,我得到一个“htmlfile：Unspecified error”.例外.我可以通过将elem.offsetParent替换为我写的这个函数的调用来解决jQuery库中的这个问题：

function IESafeOffsetParent(elem)
{
    try
    {
        return elem.offsetParent;
    }
    catch(e)
    {        
        return document.body;
    }
}

我还必须避免调用elem.getBoundingClientRect(),因为它会抛出相同的错误.对于那些感兴趣的人,我只需要在Dimensions Plugin中的jQuery.fn.offset函数中进行这些更改.

我的问题是：

>虽然这有效,但有没有更好的方法(更干净;更好的性能;无需修改jQuery库)来解决这个问题？
>如果没有,在将来更新jQuery库时,管理保持变化同步的最佳方法是什么？例如,我可以将库扩展到我从jQuery网站下载的文件中的内联之外的其他位置.

更新：

@some它不公开,但我会看到SO是否允许我将相关代码发布到这个答案中.只需创建一个ASP.NET Web应用程序(将其命名为DragAndDrop)并创建这些文件即可.不要忘记将Complex.aspx设置为起始页面.您还需要下载jQuery UI drag and drop plug in以及jQuery core

Complex.aspx

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Complex.aspx.cs" Inherits="DragAndDrop.Complex" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Untitled Page</title>
    <script src="jquery-1.2.6.min.js" type="text/javascript"></script>
    <script src="jquery-ui-personalized-1.5.3.min.js" type="text/javascript"></script>
    <script type="text/javascript">
        function initDragging()
        {
            $(".person").draggable({helper:'clone'});
            $("#trashcan").droppable({
                accept: '.person',drop: onTrashCanned
            });
        }

        $(document).ready(function(){
            initDragging();

            var prm = Sys.WebForms.PageRequestManager.getInstance();
            prm.add_endRequest(function()
            {
                initDragging();
            });
        });

        function onTrashCanned(e,ui)
        {
            var id = $('input[id$=hidID]',ui.draggable).val();
            if (id != undefined)
            {
                $('#hidTrashcanID').val(id);
                __doPostBack('btnTrashcan','');
            }

        }
    </script>
</head>
<body>
    <form id="form1" runat="server">
    <asp:ScriptManager ID="ScriptManager1" runat="server">
    </asp:ScriptManager>
    <div>
        <asp:UpdatePanel ID="updContent" runat="server" UpdateMode="Always">
    <ContentTemplate>
        <asp:LinkButton ID="btnTrashcan" Text="trashcan" runat="server" CommandName="trashcan" 
            onclick="btnTrashcan_Click" style="display:none;"></asp:LinkButton>
        <input type="hidden" id="hidTrashcanID" runat="server" />
        <asp:Button ID="Button1" runat="server" Text="Save" onclick="Button1_Click" />
        <table>
            <tr>
                <td style="width: 300px;">
                    <asp:DataList ID="lstAllPeople" runat="server" DataSourceID="odsAllPeople"
                        DataKeyField="ID">
                        <ItemTemplate>
                            <div class="person">
                                <asp:HiddenField ID="hidID" runat="server" Value='<%# Eval("ID") %>' />
                                Name:
                                <asp:Label ID="lblName" runat="server" Text='<%# Eval("Name") %>' />
                                <br />
                                <br />
                            </div>
                        </ItemTemplate>
                    </asp:DataList>
                    <asp:ObjectDataSource ID="odsAllPeople" runat="server" SelectMethod="SelectAllPeople" 
                        TypeName="DragAndDrop.Complex+DataAccess" 
                        onselecting="odsAllPeople_Selecting">
                        <SelectParameters>
                            <asp:Parameter Name="filter" Type="Object" />
                        </SelectParameters>
                    </asp:ObjectDataSource>
                </td>
                <td style="width: 300px;vertical-align:top;">
                    <div id="trashcan">
                        drop here to delete
                    </div>
                    <asp:DataList ID="lstPeopleToDelete" runat="server" 
                        DataSourceID="odsPeopleToDelete">
                        <ItemTemplate>
                            ID:
                            <asp:Label ID="IDLabel" runat="server" Text='<%# Eval("ID") %>' />
                            <br />
                            Name:
                            <asp:Label ID="NameLabel" runat="server" Text='<%# Eval("Name") %>' />
                            <br />
                            <br />
                        </ItemTemplate>
                    </asp:DataList>
                    <asp:ObjectDataSource ID="odsPeopleToDelete" runat="server" 
                        onselecting="odsPeopleToDelete_Selecting" SelectMethod="GetDeleteList" 
                        TypeName="DragAndDrop.Complex+DataAccess">
                        <SelectParameters>
                            <asp:Parameter Name="list" Type="Object" />
                        </SelectParameters>
                    </asp:ObjectDataSource>
                </td>
            </tr>
        </table>    
    </ContentTemplate>
    </asp:UpdatePanel>
    </div>
    </form>
</body>
</html>

Complex.aspx.cs

namespace DragAndDrop
{
    public partial class Complex : System.Web.UI.Page
    {
        protected void Page_Load(object sender,EventArgs e)
        {
        }

        protected List<int> DeleteList
        {
            get
            {
                if (ViewState["dl"] == null)
                {
                    List<int> dl = new List<int>();
                    ViewState["dl"] = dl;

                    return dl;
                }
                else
                {
                    return (List<int>)ViewState["dl"];
                }
            }
        }

        public class DataAccess
        {
            public IEnumerable<Person> SelectAllPeople(IEnumerable<int> filter)
            {
                return Database.SelectAll().Where(p => !filter.Contains(p.ID));
            }

            public IEnumerable<Person> GetDeleteList(IEnumerable<int> list)
            {
                return Database.SelectAll().Where(p => list.Contains(p.ID));
            }
        }

        protected void odsAllPeople_Selecting(object sender,ObjectDataSourceSelectingEventArgs e)
        {
            e.InputParameters["filter"] = this.DeleteList;
        }

        protected void odsPeopleToDelete_Selecting(object sender,ObjectDataSourceSelectingEventArgs e)
        {
            e.InputParameters["list"] = this.DeleteList;
        }

        protected void Button1_Click(object sender,EventArgs e)
        {
            foreach (int id in DeleteList)
            {
                Database.DeletePerson(id);
            }

            DeleteList.Clear();
            lstAllPeople.DataBind();
            lstPeopleToDelete.DataBind();
        }

        protected void btnTrashcan_Click(object sender,EventArgs e)
        {
            int id = int.Parse(hidTrashcanID.Value);
            DeleteList.Add(id);
            lstAllPeople.DataBind();
            lstPeopleToDelete.DataBind();
        }
    }
}

Database.cs

namespace DragAndDrop
{
    public static class Database
    {
        private static Dictionary<int,Person> _people = new Dictionary<int,Person>();
        static Database()
        {
            Person[] people = new Person[]
            {
                new Person("Chad"),new Person("Carrie"),new Person("Richard"),new Person("Ron")
            };
            foreach (Person p in people)
            {
                _people.Add(p.ID,p);
            }
        }

        public static IEnumerable<Person> SelectAll()
        {
            return _people.Values;
        }

        public static void DeletePerson(int id)
        {
            if (_people.ContainsKey(id))
            {
                _people.Remove(id);
            }
        }

        public static Person CreatePerson(string name)
        {
            Person p = new Person(name);
            _people.Add(p.ID,p);

            return p;
        }
    }

    public class Person
    {
        private static int _curID = 1;
        public int ID { get; set; }
        public string Name { get; set; }
        public Person()
        {
            ID = _curID++;
        }

        public Person(string name)
            : this()
        {
            Name = name;
        }
    }
}

解决方法

@arilanto – 我在jquery脚本之后包含了这个脚本.性能方面,它不是最好的解决方案,但它是一个快速简单的解决方案.

function IESafeOffsetParent(elem)
{
    try
    {
       return elem.offsetParent;
    }
    catch(e)
    {        
      return document.body;
    }
}

// The Offset Method
// Originally By Brandon Aaron,part of the Dimension Plugin
// http://jquery.com/plugins/project/dimensions
jQuery.fn.offset = function() {
/// <summary>
///     Gets the current offset of the first matched element relative to the viewport.
/// </summary>
/// <returns type="Object">An object with two Integer properties,'top' and 'left'.</returns>

var left = 0,top = 0,elem = this[0],results;

if ( elem ) with ( jQuery.browser ) {
    var parent     = elem.parentNode,offsetChild  = elem,offsetParent = IESafeOffsetParent(elem),doc       = elem.ownerDocument,safari2   = safari && parseInt(version) < 522 && !/adobeair/i.test(userAgent),css       = jQuery.curCSS,fixed       = css(elem,"position") == "fixed";

    // Use getBoundingClientRect if available
    if (false && elem.getBoundingClientRect) {
        var box = elem.getBoundingClientRect();

        // Add the document scroll offsets
        add(box.left + Math.max(doc.documentElement.scrollLeft,doc.body.scrollLeft),box.top  + Math.max(doc.documentElement.scrollTop,doc.body.scrollTop));

        // IE adds the HTML element's border,by default it is medium which is 2px
        // IE 6 and 7 quirks mode the border width is overwritable by the following css html { border: 0; }
        // IE 7 standards mode,the border is always 2px
        // This border/offset is typically represented by the clientLeft and clientTop properties
        // However,in IE6 and 7 quirks mode the clientLeft and clientTop properties are not updated when overwriting it via CSS
        // Therefore this method will be off by 2px in IE while in quirksmode
        add( -doc.documentElement.clientLeft,-doc.documentElement.clientTop );

    // Otherwise loop through the offsetParents and parentNodes
    } else {

        // Initial element offsets
        add( elem.offsetLeft,elem.offsetTop );

        // Get parent offsets
        while ( offsetParent ) {
            // Add offsetParent offsets
            add( offsetParent.offsetLeft,offsetParent.offsetTop );

            // Mozilla and Safari > 2 does not include the border on offset parents
            // However Mozilla adds the border for table or table cells
            if ( mozilla && !/^t(able|d|h)$/i.test(offsetParent.tagName) || safari && !safari2 )
                border( offsetParent );

            // Add the document scroll offsets if position is fixed on any offsetParent
            if ( !fixed && css(offsetParent,"position") == "fixed" )
                fixed = true;

            // Set offsetChild to previous offsetParent unless it is the body element
            offsetChild  = /^body$/i.test(offsetParent.tagName) ? offsetChild : offsetParent;
            // Get next offsetParent
            offsetParent = offsetParent.offsetParent;
        }

        // Get parent scroll offsets
        while ( parent && parent.tagName && !/^body|html$/i.test(parent.tagName) ) {
            // Remove parent scroll UNLESS that parent is inline or a table to work around Opera inline/table scrollLeft/Top bug
            if ( !/^inline|table.*$/i.test(css(parent,"display")) )
                // Subtract parent scroll offsets
                add( -parent.scrollLeft,-parent.scrollTop );

            // Mozilla does not add the border for a parent that has overflow != visible
            if ( mozilla && css(parent,"overflow") != "visible" )
                border( parent );

            // Get next parent
            parent = parent.parentNode;
        }

        // Safari <= 2 doubles body offsets with a fixed position element/offsetParent or absolutely positioned offsetChild
        // Mozilla doubles body offsets with a non-absolutely positioned offsetChild
        if ( (safari2 && (fixed || css(offsetChild,"position") == "absolute")) ||
            (mozilla && css(offsetChild,"position") != "absolute") )
                add( -doc.body.offsetLeft,-doc.body.offsetTop );

        // Add the document scroll offsets if position is fixed
        if ( fixed )
            add(Math.max(doc.documentElement.scrollLeft,Math.max(doc.documentElement.scrollTop,doc.body.scrollTop));
    }

    // Return an object with top and left properties
    results = { top: top,left: left };
}

function border(elem) {
    /// <summary>
    ///     This method is internal.
    /// </summary>
    /// <private />
    add( jQuery.curCSS(elem,"borderLeftWidth",true),jQuery.curCSS(elem,"borderTopWidth",true) );
}

function add(l,t) {
    /// <summary>
    ///     This method is internal.
    /// </summary>
    /// <private />
    left += parseInt(l,10) || 0;
    top += parseInt(t,10) || 0;
}

return results;
};

（编辑：李大同）

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