javascript函数调用而不单击超级链接按钮为何

Question

Three hyperlink button and i call a javascript function to onclick button ,i store the link button id in respective session after check the condition but the function are call without click hyper link button and it allweys execute last session values

<li><a href="" id="link_leave" onclick="showBtton(this.id)">Leave Policy</a></li>
 <li><a href="" id="link_tour" onclick="showBtton(this.id)">Tour policy </a></li>
 <li><a href="" id="link_it" onclick="showBtton(this.id)">IT Policy</a> </li>

java script function call

<script lang="javascript" >

    {
        var itsPostBack = <%=Page.IsPostBack ? "true" : "false" %>;
        alert(itsPostBack);
        if(itsPostBack!=false)
        {
            function showBtton(id) 
            {


                if ("link_leave"==id) 
                {
                    var a = "leave_button";
                    alert(a);

                    <%--  '<%Session["identify"] = "' + a + '"; %>';  --%>
                    '<%Session["identify"] = "leave_button"; %>';

                    var Session_value = "";
                    Session_value = '<%=Session["identify"] %>'; 
                    Session_value =Session["identify"] ;
                    alert(Session_value);
                    javascript: window.open('policy.aspx', '_blank');
                }
                if ("link_tour"==id)
                {
                    var a = "tour_button";
                    alert(a);

                    <%--  '<%Session["identify"] = "' + a + '"; %>'; --%>
                    '<%Session["identify"] = "tour_button"; %>';

                    var Session_value = "";
                    Session_value = '<%=Session["identify"] %>';
                    Session_value = Session["identify"];
                    alert(Session_value);
                    javascript: window.open('policy.aspx', '_blank');
                }

                if ("link_it"==id)
                {
                    var a = "it_button";
                    alert(a);

                    <%--  '<%Session["identify"] = "' + a + '"; %>'; --%>
                    '<%Session["identify"] = "it_button"; %>';

                    var Session_value = "";
                    Session_value = '<%=Session["identify"] %>';
                    Session_value = Session["identify"];
                    alert(Session_value);
                    javascript: window.open('policy.aspx', '_blank'); 

                }

            } 
        }
    }

    </script>

Answer 1

The issue is you are trying to modify the server side ASP.NET session using Javascript which is not possible as once you run Javascript code it is run on the clients browser which has no direct access to the session on the server.

You have a few choices:

1. Send the button ID to the server via an AJAX call and then retrieve it via an AJAX call when needed
2. Use local session storage to implement a client side session which is stored in the browser rather than the server so you can modify it through Javascript. Please see this page for more details: https://developer.mozilla.org/en/docs/Web/API/Window/sessionStorage
3. Another option would be to pass the button id as a query string parameter in the URL so you can avoid the session.