Pass javascript var to asp.net code behind (c#)

Question

I have a problem, I want to pass javascript var to server side.

I want to pass the value of var autocomplete to string named Event_Address;

aspx.cs:

protected void ButtonAddEvent_Click(object sender, EventArgs e)
{
    string Event_Address =hdnfldVariable.Value;
}

aspx:

var autocomplete;

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

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

<asp:Button ID="ButtonAddEvent" runat="server" Text="הוסף אירוע חדש" 
        Font-Bold="True" Font-Names="Gisha" Font-Size="17pt" ForeColor="Blue" 
        onclick="ButtonAddEvent_Click" 
        style="z-index: 1; left: 497px; top: 774px; position: absolute" />
</asp:Content>

Use `var hdnfldVariable = document.getElementById("<%= hdnfldVariable.ClientID %>")` if the hidden field ClientID is dynamic one. — Tetsuya Yamamoto, Mar 01 '17 at 07:31
thank for your answer , my code working , i tried to pass address input that powerd by script of google maps, so i think my code is dynamic. — גל אברג'יל, Mar 01 '17 at 07:36
take a look here https://forums.asp.net/t/1211504.aspx?Passing+values+from+Javascript+to+ASPX — Mikhail Tulubaev, Mar 01 '17 at 07:36
If you are using a master page then document.getElementById('<%= hdnfldVariable.ClientID%>').value = autocomplete; It should then be visible in code behind. — , Mar 01 '17 at 07:40

score 1 · Answer 1 · edited May 23 '17 at 12:17

In addition to teo van kot's answer, if the ClientID for HiddenField is a dynamic one, it should be defined as dynamic ClientID like this:

var autocomplete = "[somevalue]";

    <script type="text/javascript">
    var somefunction = function() {
        // set this if you have dynamic ClientID
        var hdnfldVariable = document.getElementById("<%= hdnfldVariable.ClientID %>");
        hdnfldVariable.value = autocomplete;
    }
    </script>

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

       <asp:Button ID="ButtonAddEvent" runat="server" Text="הוסף אירוע חדש" 
        Font-Bold="True" Font-Names="Gisha" Font-Size="17pt" ForeColor="Blue" 
        onclick="ButtonAddEvent_Click"
    OnClientClick="somefunction();"
        style="z-index: 1; left: 497px; top: 774px; position: absolute" />
</asp:Content>

Reference:

Passing values from javascript to code behind in ASP.NET

score 0 · Answer 2 · answered Mar 01 '17 at 07:34

If you want to call your js function on Button click you shold add it to OnClientClick attribute. like this:

var autocomplete;

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

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

       <asp:Button ID="ButtonAddEvent" runat="server" Text="הוסף אירוע חדש" 
        Font-Bold="True" Font-Names="Gisha" Font-Size="17pt" ForeColor="Blue" 
        onclick="ButtonAddEvent_Click" 
        OnClientClick="somefunction();"
        style="z-index: 1; left: 497px; top: 774px; position: absolute" />
</asp:Content>

score 0 · Answer 3 · edited May 23 '17 at 12:00

0

Either you can save the value of your "autocomplete" to hidden field or you can use ajax method to call a c# function , to pass the value from front-end to back end.

or in your case use the attrbute property to change the value .

please refer this link for the ajax call Ajax method call

edited May 23 '17 at 12:00

Community

1
1

answered Mar 01 '17 at 07:35

1

how can i use ajax? can you please typed it? – גל אברג'יל Mar 01 '17 at 07:40

score 0 · Answer 4 · answered Mar 01 '17 at 07:40

You can use [Web Method] in server side. You should add using System.Web.Services; to your cs code for using web methods. Here is the steps:

Change your button; use html button instead of server side button.
Create js function and call it with onclick event in button.
Pass your variable with PageMethods.YourWebMethod(yourParam); in js.

Then you have it in server side web method. Here is an ex for you:

 function JsFunctionOnclick(){ 
  PageMethods.MyPageMethod(myParameter);
 }

and this is server side:

[WebMethod]
public static void MyPageMethod(string param)
{
    //do something
}

Be sure your web method is static Good luck.

Pass javascript var to asp.net code behind (c#)

4 Answers4