Javascript regex only letters and spaces (with JQuery)

 

<script>

//regex expression:
var reg_name_lastname = /^[a-zA-Z\s]*$/;

//Validation to the user_name input field
if(!reg_name_lastname.test($('#user_name').val())){ //
    alert("Correct your First Name: only letters and spaces.");
    valid = false;
}

</script>