Event를 Bind하는 예제

WebSocket을 Send하는 부분에서 이벤트를 bind하는 것처럼 쓰는 예제

var WebsocketWrapper = function(url) {
        
        if (!window.WebSocket) {
            window.WebSocket = window.MozWebSocket;
        }
        
        let conn = new WebSocket(url);
 
        let callbacks = {};
        
        this.bind = function(event_name, callback) {
            callbacks[event_name] = callbacks[event_name] || [];
            callbacks[event_name].push(callback);
            return this;// chainable
        };
        
        this.remove = function(event_name) {
            delete callbacks[event_name];
        };
 
        this.send = function(event_name, event_data) {
            // *var payload = JSON.stringify({event:event_name, data: event_data});
            conn.send( event_data ); // <= send JSON data to socket server
            return this;
        };
        
        this.getSocket = function () {
            return conn;
        };
 
        // dispatch to the right handlers
        conn.onmessage = function(evt) {
            //* var json = JSON.parse(evt.data)
            
            var ta = document.getElementById('responseText');
            ta.value = ta.value + '\n' + evt.data
            
            //* dispatch(json.event, json.data)
            dispatch('res' + evt.data, evt.data)
        };
 
        conn.onclose = function() {
            var ta = document.getElementById('responseText');
            ta.value = ta.value + "\r\nWeb Socket closed";
            
            dispatch('close',null)
        };
        
        conn.onopen = function() {
            var ta = document.getElementById('responseText');
            ta.value = "Web Socket opened!";
            
            dispatch('open',null)
        };
 
        let dispatch = function(event_name, message) {
            var chain = callbacks[event_name];
            if (typeof chain == 'undefined') return; // no callbacks for this event
            for(var i = 0; i < chain.length; i++) {
                chain[i]( message )
            }
            
            //* 1회성으로만 쓰기 위해서 
            delete callbacks[event_name];
        }
    };

호출하는 쪽

    function someSend(arg) {
        if (socket.getSocket().readyState != WebSocket.OPEN) {
            socket = new WebsocketWrapper(wsUrl);
            socket.bind('open', function() {
                sendProc(arg);
            });
        } else {
            sendProc(arg);
        }
    }