Javascript从后面的c#代码中读取公共变量

Question

Trying to use public properties from C# code behind and want to read the variable value from a JavaScript function

JavaScript function:

function IsAgentInProgram()
{
    var optStatus = "<%=AgentOptInStatus%>";

    if (optStatus == "True")
        alert("You are opted in!");
    else
        alert ("You are opted OUT");
}

C# code behind

public bool AgentOptInStatus;

private void Page_Load(object sender, System.EventArgs e)
{
    this.AgentOptInStatus = true;

}

This does not work. Output comes back as You are opted OUT . I also did an alert on optStatus and it comes back with: "<%=AgentOptInStatus%>"

Am I missing something?

Answer 1

You cannot read the client side variables directly in the codebehind. What you can do is creating a hidden field and setting the value with javascript, then you can read it in c#.

<asp:HiddenField ID="hdnfldVariable" runat="server" />

JS:

<script type="text/javascript">
        var somefunction = function () {
            var hdnfldVariable = document.getElementById('hdnfldVariable');
            hdnfldVariable.value = 'value from javascript';
        }
    </script>

c# :

string selected = hdnfldVariable.Value.ToString();

Another option is to make an HTTP request to the server to call a function from a controller passing the data as parameters.