如何使用javascript设置asp.net的label文本并在服务器端获取设置值

Question

I have two questions about javascript and asp.net , the result i want is : make a label same change when textbox keypress, here are what i do :

in asp.net page:

<form id="form1" runat="server">
<div>

    <asp:TextBox ID="TextBox1" runat="server" onkeypress="okpress();"></asp:TextBox>
    <br />
    <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
    <br />
    <asp:Button ID="Button1" runat="server" Text="Button" OnClick="test1" />
</div>
</form>

and this is my script:

<script type="text/javascript">
    function okpress() {
        //alert('Your keypress on TextBox1.');
        var v1 = document.getElementById("Label1");
        v1.innerHTML = document.getElementById("TextBox1").value;
    }
</script>

when i test the result , i find label1 's text do change when textbox1 keypress , but it is strange that label1 's text always lack one char with textbox1 , that is to say , if i type "abcd" in textbox1, label1 only display "ab".

another question is about the button , when i write this code in .cs file:

    protected void test1(object sender, EventArgs e)
    {
        string s1 = Label1.Text;
        return;
    }

and add a breakpoint at "return" , i find no matter whatever i type in textbox1 , the variable s1 always is "Label1"

i think this two question maybe easy to experience one , but i just can not solve it, thanks for any helps.

Answer 1

You can change your Keypress event to Keyup event and try with the same Script..

<asp:TextBox ID="TextBox1" runat="server" onKeyup="okpress();"></asp:TextBox>

And for the second question,If we set the innerHtml of a label at client side it is difficult to access it on server side ..

In the second case you can use this approach.

Declare a Hidden input Control ..

 <input type="Hidden" id="Hidden1" value="" clientidnode="Static" runat="server">

After that you can set the innerHtml of the label to this control.

document.getElementid('Hidden1').value=v1.innerHTML;

After that you can access the Hidden control in your server side as shown below..

protected void test1(object sender, EventArgs e)
    {
        string s1 = Hidden1.value;
        return;
    }