How To Pass The Textbox Text From Code Behind To JS

I want to pass the textbox text from code behind to JS.

Code:

protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
TxtOpVolMT.Attributes.Add("onkeypress", "javascript: return Limit('" + TxtOpVolMT.Text + "');");

Code:

<script type="text/javascript" language="javascript">
function Limit(Text) {
alert (Text);
return true ;
}

But alert is not displaying the value,y so evrytime alert is displaying but do not have any value.