i have a problem with this simple login with ajax is when i click login the page refresh when it should not -_-
My form
<div class="user_login">
            <form action="<?php echo base_url('welcome/login');?>" method="post" id="login-usr-frm">
                <label>Email / Username</label>
                <input type="text" name="user"/>
                <br />
                <label>Password</label>
                <input type="password" name="password" />
                <br />
                <div class="checkbox">
                    <input id="remember" type="checkbox" />
                    <label for="remember">Remember me on this computer</label>
                </div>
                <div class="action_btns">
                    <div class="one_half"><a href="#" class="btn back_btn"><i class="fa fa-angle-double-left"></i> Back</a></div>
                    <div class="one_half last"><input type="submit" id="lgn-btn-red" class="btn btn_red" value="Login"></div>
                </div>
            </form>
            <a href="#" class="forgot_password">Forgot password?</a>
        </div>
My jquery code
<script type="text/javascript">
    $(function (){
        $("#login-usr-frm").submit(function(event) {
            event.preventDefault();
            var url = $(this).attr('action');
            var postData = $(this).serialize();
            $.post(url, postData, function (o))
        }, 'json');
        });
    });
</script>
i can't find the issue , please help ! :)