var LoginUnique = Class.create();
LoginUnique.prototype = {
    initialize: function( field_id, message_id) {
        this.message_id = message_id;
        this.field = document.getElementById( field_id );
        if (typeof this.field == 'undefined') {return;}
        // Observe blur on field    
        Event.observe(this.field, 'blur', this.checkName.bindAsEventListener(this));
    },
    checkName: function() {
    if( typeof this.field != 'undefined' )
    {
            var name = this.field.value;
            // don't hit server unless username is well-formed
            var re = /^([A-Za-z])[a-zA-Z0-9]{2,25}$/;
            if( name.match( re ))
                new Ajax.Request('/signup/is_member_name_taken', {asynchronous:true, parameters:'login='+name+'&message_html_id='+this.message_id});
            }
    }
};