function  populateText（）
 {
 if （ document  .getElementById （'  chechboxid'）。已选中）
 {
 var  str =  document  .getElementById（'  textbox1id）.value; //在其中输入数据的文本框
 document.getElementById（' textbox2id）.Value = str; 
} 
} 


将javascrip  function 称为复选框 in  .aspx页面的pageload方法

 pageload（）
 {

 checkboxid.attributes.add（  onclick，  populateText（）;跨度>）; 
} 

你可以在javascript中这样做，

< asp：TextBox ID = txt1 runat = server > < / asp：TextBox >
< asp：TextBox ID = txt2 RUNAT 的pan> = server > < / asp：TextBox >
< asp：CheckBox ID = chk runat = 服务器 文字 = 复制 onclick = copyvalue（） / >
< script type = text / javascript >
function copyvalue（）{
var txt1 = document.getElementById（ <％ = txt1.ClientID ％> ）。value;
document.getElementById（<％ = txt2.ClientID ％> ）。 value = txt1;
}
< / script >

或

with jquery

 <   asp：TextBox     ID   =  txt1    runat   =  server >  <   / asp：TextBox  >  
<   asp：TextBox     ID   =  txt2    runat   =  server >  <   / asp：TextBox  >  
<   asp：CheckBox     ID   =  chk    runat   =  server   文本  = 复制  /  >  
<   script     src   =  Scripts / jquery-1.4.1.min.js   类型  =  text / javascript >  <   / script  >  
<   script     type   =  text / javascript >  

（＃ <％ = chk.ClientID ％> ）。change（ function（）{
var txt1 =

Hi i am using two text box when i enter the value in the one text box and after i pressing the check box the text box value need to copy into other text box how it is possible in Java script

Can u help?

function populateText()
{
 if(document.getElementById('chechboxid').checked)
 {
  var str=document.getElementById('textbox1id).value;// textbox in which you enter data
  document.getElementById('textbox2id).Value= str;
}
}


call the javascrip function as attribute to checkbox in pageload method of your .aspx page

 pageload()
 {

 checkboxid.attributes.add("onclick","populateText();");
}

Hi,
You can do like this in javascript,

<asp:TextBox ID="txt1" runat="server"></asp:TextBox>
<asp:TextBox ID="txt2" runat="server"></asp:TextBox>
<asp:CheckBox ID="chk" runat="server" Text="Copy" onclick="copyvalue()"/>
<script type="text/javascript">
function copyvalue() {
    var txt1 = document.getElementById("<%= txt1.ClientID %>").value;
    document.getElementById("<%= txt2.ClientID %>").value = txt1;
}
</script>

OR
with jquery

<asp:TextBox ID="txt1" runat="server"></asp:TextBox>
    <asp:TextBox ID="txt2" runat="server"></asp:TextBox>
    <asp:CheckBox ID="chk" runat="server" Text="Copy"/>
<script src="Scripts/jquery-1.4.1.min.js" type="text/javascript"></script>
<script type="text/javascript">

("#<%= chk.ClientID %>").change(function () { var txt1 =