观察者模式

<script>
    var Paper = function() {
        this.customers = [];
    };
    
    Paper.prototype.sendPaper = function(data) {
        for(var i = 0, len = this.customers.length; i < len; i++) {
            this.customers[i].receive(data);
        }
    };

    var Customer = function(param) {
        this.name = param.name;
    };
    
    Customer.prototype.subscribe = function(paper) {
        var customers = paper.customers;
        var isExist = false;
        for(var i = 0, len = customers.length; i < len; i++){ 
            if(customers[i] === this){
                isExist = true;
                break;
            }
        }
        
        if(!isExist) {
            customers.push(this);
        }
        
        return this;
    };
    
    Customer.prototype.receive = function(data) {
        console.log(this.name + "接收了 " + data.paperName);
    };
    
    var Beijingpaper = new Paper();
    var Tianjingpaper = new Paper();
    var Shanghaipaper = new Paper();
    
    var Jim = new Customer({name: "Jim"});
    var Bily = new Customer({name: "Bily"});
    
    Jim.subscribe(Beijingpaper).subscribe(Tianjingpaper);
    Bily.subscribe(Shanghaipaper).subscribe(Tianjingpaper);
    
    Shanghaipaper.sendPaper({paperName:"shagnhai"});
    Tianjingpaper.sendPaper({paperName:"Tianjing"});
    Beijingpaper.sendPaper({paperName:"beijing"});
    
</script>

 

<script>
    function Click() {
        this.handlers = [];
    }
    
    Click.prototype = {
        subscribe: function(fn) {
            this.handlers.push(fn);
        },
        unsubscribe: function(fn) {
            this.handlers = this.handlers.filter(function(item) {
                if(item !== fn) {
                    return item;
                }
            });
        },
        fire: function(o, thisObj) {
            var scope = thisObj || window;
            this.handlers.forEach(function(item) {
                item.call(scope, o);
            });
        }
    };
    
    var log = (function() {
        var log = "";
        return {
            add: function(msg) {log += msg + "
";},
            show: function() { alert(log); log = "";}
        };
    })();
    
    function run() {
        var clickHandler = function(item) {
            log.add("fired: " + item);
        };
        
        var click = new Click();
        
        click.subscribe(clickHandler);
        click.fire("event #1");
        
        log.show();
    }
    run();
</script>