retrieve value from javascript function in codebehind

Question

How can I retrieve value from javascript function in codebehind, on page load .. javascript function like :

<script type="text/javascript">
        function isIFrame() {
            var isInIFrame = (top.location != self.location);
            if (isInIFrame) {
                return "inside";
            }
            else {
                return "outside";
            }
        }
    </script>

and code behind like :

protected void Page_Load(object sender, EventArgs e)
    {
        string resutOfExecuteJavaScript = "";
        // resutOfExecuteJavaScript = isIFrame(); // from javascript

        if (resutOfExecuteJavaScript == "inside")
        {
            // do something
        }
        else
        {
            // do something
        }
    }

thank you.

Solution 1

You cannot directly call a client side javascript method from server side code . For that first you need to assign the function result to value of some hidden variable and then access it in server side

Suppose you have an hidden field like this

<input type="hidden" runat="server" id="hdnVal"/>

then you can set the value as below

document.getElementById("hdnVal").value=isIFrame();

then at serve side

 string resutOfExecuteJavaScript = hdnVal.Value;

Solution 2

using _doPostBack, you can solve this one

      <script type="text/javascript">
             function isIFrame() {
            var isInIFrame =(top.location != self.location);
            var result;
            if (isInIFrame) { 
                result="inside";
             }
           else
             {
             result ="outside";
             }
           __doPostBack('callPostBack', result);
        </script>
    </head>

In code behind section

protected void Page_Load(object sender, EventArgs e)
{
    this.ClientScript.GetPostBackEventReference(this, "arg");
    if (IsPostBack)
    {
        string eventTarget = this.Request["__EVENTTARGET"];
        string eventArgument = this.Request["__EVENTARGUMENT"];

        if (eventTarget != String.Empty && eventTarget == "callPostBack")
        {
            if (eventArgument == "inside"){   
               //do something
               }
           else if(eventArgument == "outside")
            {
           //do something
           }
       }
    else
    {
       // set the button click
        btnclick.Attributes.Add("onClick", "isIFrame();");
    }
}

Below link will help you out to get more idea.

http://www.dotnetcurry.com/ShowArticle.aspx?ID=203