//ConcreteState
function CloseState() {
    this.open = function(c) {
        console.log("open the connection");
        c.setState(new OpenState());
    }

    this.close = function(c) {
        console.log("connection is already closed");
    }
}

//ConcreteState
function OpenState() {
    this.open = function(c) {
        console.log("connection is already open");
    }

    this.close = function(c) {
        console.log("close the connection");
        c.setState(new CloseState());
    }
}

//Context
function Connection() {
    var state = new CloseState();

    this.open = function() {
        state.open(this);
    }

    this.close = function() {
        state.close(this);
    }

    this.setState = function(sState) {
        state = sState;
    }
}

//Client
var con = new Connection();
con.open();
//printed: open the connection
con.open();
//printed: connection is already open
con.close();
//printed: close the connection
con.close();        
//printed: connection is already closed