How to call javascript function from code-behind

Question

I wrote a javascript with a asp.net page.

In Asp.net Page

<HTML> <HEAD>
     <script type="text/javascript">
      function Myfunction(){
          document.getElementId('MyText').value="hi";
      }
      </script>
</HEAD> <BODY>
<input type="text" id="MyText" runat="server" /> </BODY>

In Code-behind

 Private Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)
  Handles Me.Load
       If Session("My")= "Hi" Then
          I want to call "Myfunction" javascript function
       End If 
 End Sub

How can I do?

possible duplicate of How to call javascript function from code-behind — outis
– outis, Commented Jan 31, 2011 at 8:02
do you really want to call the function from the code-behind, or do you want function to run when the page load? I think it is the last alternative you want. — Tomas Jansson
– Tomas Jansson, Commented Jan 31, 2011 at 8:07

Jacob · Accepted Answer · 2012-10-12 15:54:54Z

80

One way of doing it is to use the ClientScriptManager:

Page.ClientScript.RegisterStartupScript(
    GetType(), 
    "MyKey", 
    "Myfunction();", 
    true);

edited Oct 12, 2012 at 15:54

answered Jan 31, 2011 at 8:01

Jacob

79k24 gold badges159 silver badges245 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

Antoine Pelletier Over a year ago

Seem like the best way is yours, but what does "MyKey" is ?

Jacob Over a year ago

The key is just a unique identifier to help avoid emitting the same script twice. It can be anything.

Gabriel Bernardone Over a year ago

the best solution, very simple

Pranesh Janarthanan Over a year ago

the key shall be a GUID!

Matthew Lock Over a year ago

See here if you want the javascript function to execute after the page has loaded stackoverflow.com/a/40335689/74585

TylerH · Accepted Answer · 2020-11-06 22:35:48Z

44

This is a way to invoke one or more JavaScript methods from the code behind. By using Script Manager we can call the methods in sequence. Consider the below code for example.

ScriptManager.RegisterStartupScript(this, typeof(Page), "UpdateMsg", 
    "$(document).ready(function(){EnableControls();
    alert('Overrides successfully Updated.');
    DisableControls();});", 
true);

In this first method EnableControls() is invoked. Next the alert will be displayed. Next the DisableControls() method will be invoked.

edited Nov 6, 2020 at 22:35

TylerH

21.3k84 gold badges84 silver badges121 bronze badges

answered Mar 19, 2014 at 9:18

Deepak Kothari

1,7931 gold badge27 silver badges41 bronze badges

Comments

spacer · Accepted Answer · 2017-02-24 05:18:06Z

14

There is a very simple way in which you can do this. It involves injecting a javascript code to a label control from code behind. here is sample code:

<head runat="server"> 
    <title>Calling javascript function from code behind example</title> 
        <script type="text/javascript"> 
            function showDialogue() { 
                alert("this dialogue has been invoked through codebehind."); 
            } 
        </script> 
</head>

..........

lblJavaScript.Text = "<script type='text/javascript'>showDialogue();</script>";

Check out the full code here: ~~http://softmate-technologies.com/javascript-from-CodeBehind.htm~~ (dead)
Link from Internet Archive: https://web.archive.org/web/20120608053720/http://softmate-technologies.com/javascript-from-CodeBehind.htm

edited Feb 24, 2017 at 5:18

spacer

1,5771 gold badge11 silver badges20 bronze badges

answered Jun 2, 2012 at 7:49

evaaggy

1871 silver badge4 bronze badges

2 Comments

Hugo Nava Kopp Over a year ago

Unfortunately the link is broken :-(

cymorg Over a year ago

Loving this solution - it almost feels like cheating. I suspect it may not be suitable for every scenario but I'm hard pressed to think of a case where it wouldn't work.

Max Alexander Hanna · Accepted Answer · 2019-04-16 15:31:19Z

If the order of the execution is not important and you need both some javascript AND some codebehind to be fired on an asp element, heres what you can do.

What you can take away from my example: I have a div covering the ASP control that I want both javascript and codebehind to be ran from. The div's onClick method AND the calendar's OnSelectionChanged event both get fired this way.

In this example, i am using an ASP Calendar control, and im controlling it from both javascript and codebehind:

Front end code:

        <div onclick="showHideModal();">
            <asp:Calendar 
                OnSelectionChanged="DatepickerDateChange" ID="DatepickerCalendar" runat="server" 
                BorderWidth="1px" DayNameFormat="Shortest" Font-Names="Verdana" 
                Font-Size="8pt" ShowGridLines="true" BackColor="#B8C9E1" BorderColor="#003E51" Width="100%"> 
                <OtherMonthDayStyle ForeColor="#6C5D34"> </OtherMonthDayStyle> 
                <DayHeaderStyle  ForeColor="black" BackColor="#D19000"> </DayHeaderStyle>
                <TitleStyle BackColor="#B8C9E1" ForeColor="Black"> </TitleStyle> 
                <DayStyle BackColor="White"> </DayStyle> 
                <SelectedDayStyle BackColor="#003E51" Font-Bold="True"> </SelectedDayStyle> 
            </asp:Calendar>
        </div>

Codebehind:

        protected void DatepickerDateChange(object sender, EventArgs e)
        {
            if (toFromPicked.Value == "MainContent_fromDate")
            {
                fromDate.Text = DatepickerCalendar.SelectedDate.ToShortDateString();
            }
            else
            {
                toDate.Text = DatepickerCalendar.SelectedDate.ToShortDateString();
            }
        }

皮皮shrimp · Accepted Answer · 2021-04-06 03:23:49Z

0

asp:run javascript method

Add this line to the bottom of the page before </form> tag, at least under the js function you wrote.

the reason of doning this is avoid calling your method before your browse knowing what is the funcion and finally do nothing.

<% Response.Write($"<script>yourfunction('{Config.id}');</script>"); %>

ps: I've tried all methods up there but nothing worked fine for me. And I figure out this easy and wonder way of calling js method on my own!

answered Apr 6, 2021 at 3:23

皮皮shrimp

354 bronze badges

Collectives™ on Stack Overflow

How to call javascript function from code-behind

5 Answers 5

5 Comments

Comments

2 Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

5 Answers 5

5 Comments

Comments

2 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related