javascript is not working from asp.net to change simple label text

Question

I have been through 4hrs of posts now. I can not get this js code to work. This is the latest iteration, I have tried many combinations.

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="WebFormRedisTest.WebForm1" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>

<script type="text/javascript">

    function updateText(strData) {
        debugger;
        document.getElementById("<%=lbl.ClientID%>").innerHTML(strData);
    }

</script> 
</head>
<body>
    <form id="form1" runat="server">
     <asp:Button ID="Button1" runat="server" Text="Button" OnClick="Test_OnClientClick"/>

        <div>
        </div>
        <asp:Label ID="lbl" runat="server" Text="Label" ClientIDMode="Static"></asp:Label>
    </form>
</body>
</html>

public void Test_OnClientClick(object sender, EventArgs e)
        {
            Console.WriteLine("test");
            ScriptManager.RegisterStartupScript(this, this.GetType(), "updateText", "updateText('test');", true);
        }

Open the devtools of your browser and check for error messages in the console. Also check whether the generated JavaScript is what you expect — Hans Keﬆing
– Hans Keﬆing, Commented Feb 28, 2020 at 21:58
can you share more details about question, what are you trying to do? — Learning
– Learning, Commented Mar 1, 2020 at 9:31
sorry i thought it was obvious that i'm just trying in this simplified version to change the text of a label via js. I know it's something simple as i've done this before but can't get the syntax correct, it is just not working to change label text. — MX313
– MX313, Commented Mar 2, 2020 at 13:14

William McDonald · Accepted Answer · 2020-03-02 14:12:50Z

2

I don't think innerHTML() is a function. I think you have to write something like:

document.getElementById("<%=lbl.ClientID%>").innerHTML = strData;

Update:

I started a quick webforms project and this is what my script tag section looks like:

<script type="text/javascript">

    function updateText(strData) {
        debugger;
        document.getElementById("lbl").innerHTML = strData;
    }

</script>

The back-end is just like yours.

public void Test_OnClientClick(object sender, EventArgs e)
{
    ScriptManager.RegisterStartupScript(this, this.GetType(), "updateText", "updateText('test');", true);
}

edited Mar 2, 2020 at 14:12

answered Feb 28, 2020 at 21:39

William McDonald

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1 Comment

William McDonald Over a year ago

If you are trying to change the text of the label specifically, you probably need to use "document.getElementById().innerText =". I've just used both innerHTML and innerText and they both work for me.

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