实现简单的订阅模式

function Events() {
    this.on = function() {
        if (!this.handles) {
            this.handles = {}
        }
        
        if (!this.handles[eventName]) {
            this.handles[eventName] = []
        }
        
        this.handles[eventName].push(callBack)
    }
    
    this.emit = function(eventName, obj) {
        if (this.handles[eventName]) {
            for(var i = 0; i < this.handles[eventName].length; i++) {
                 this.handles[eventName][i](obj)
            }
        }
    }
    
    return this
}

// 调用实例
var events = new Events()
events.on('say', function(name) {
    console.log('Hello', name)
})

events.emit('say', 'jony yu')