Question

I have a form, I want to check the username is availability. I that I have html textbox, in Onclcik I’m calling java script function. The script has to call the Action methods in controller. Based upon the username availability it has to return either 1 or 0. I have tried Json. But its is showing “Microsoft JScript runtime error: ‘$’ is undefined”. Can anyone help me in this.

Answer 1

If you get that message it means you’re trying to use jQuery but you haven’t included the library. You can use Google’s CDN.
I guess you’ve used Ajax to call. Something like this:

$.ajax({
    type: 'POST',
        url: '<%=Url.Action("Your Action", "Your Controller")%>',
    data: { userName: $('#UserName').val(), password: $('#Password').val() },
        dataType: 'json',
        complete: function(XMLHttpRequest, textStatus) {
    // User your JSON response.
    }
});

If you’re using a POST you have to decorate your action with the attribute [HttpPost]
and remember to specify JsonRequestBehavior.DenyGet when you return your JSON object:

[HttpPost]
public JsonResult CheckUserName(string userName, string password)
{
    // notification: your object
    return (Json(notification, JsonRequestBehavior.DenyGet));
}