Hi nauna,
You can handle the TextBox value from Controller.
Check this example. Now please take its reference and correct your code.
Model
public class CustomerModel
{
public bool Sw { get; set; }
public string AboutMe { get; set; }
}
Controller
public class HomeController : Controller
{
// GET: /Home/
public ActionResult Index()
{
CustomerModel model = new CustomerModel();
model.Sw = true;
if (model.Sw)
{
model.AboutMe = "select";
}
return View(model);
}
}
View
<%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage<_CheckBox_Based_TextBox_MVC.Models.CustomerModel>" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>Index</title>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.2/css/bootstrap.min.css" />
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<script type="text/javascript">
$(function () {
$('[id*=chkStatus]').on('click', function () {
if ($(this).is(':checked')) {
$('[id*=txtAboutMe]').val("select");
}
else {
$('[id*=txtAboutMe]').val("");
}
});
});
</script>
</head>
<body>
<div class="form-group">
<%:Html.LabelFor(model => model.Sw)%>
<div class="col-md-10">
<div class="checkbox">
<%:Html.CheckBoxFor(model => model.Sw, new { id="chkStatus", @class = "form-control" } )%>
</div>
</div>
</div>
<br />
<div class="form-group">
<%:Html.LabelFor(model => model.AboutMe)%>
<div class="col-md-10">
<%:Html.TextBoxFor(model => model.AboutMe, new { id = "txtAboutMe", @class = "form-control" })%>
</div>
</div>
</body>
</html>
Screenshot
