Why am I getting this error, when I'm trying to get a response from a file on my own server?

$.get("http://www.example.com/user.php?q=" + client + "", function(response) { 

if(response == "invalid"){
console.log("invalid login");       

    return;
}

And btw, the string client is mentioned already in the code.

And jquery is included.

http://i.gyazo.com/693e6633d211ab6da79598e75c6dde58.png