function Observer(){this.fns = []}
Observer.prototype = {
subscribe:function(fn){
this.fns.push(fn)
},
unsubscribe:function(fn){
this.fns = this.fns.filter((cb)=>{if(cb != fn){return true}})
},
update:function(o,thisobj){
let scope = thisobj || window
this.fns.forEach((val)=>{
val.call(scope,o)
})
}
}
//以下为举的简单例子
let o = new Observer()
let f1 = function(data){
console.info(`li:${data}`)
}
let f2 = function(data){
console.info(`wang:${data}`)
}
let f3 = function(data){
console.info(`williem:${data}`)
}
o.subscribe(f1)
o.subscribe(f2)
o.subscribe(f3)
o.update("tom回来了")
/*输出示例*/
li:tom回来了
wang:tom回来了
williem：tom回来了
o.unsubscribe(f1)
/*输出示例*/
wang:tom回来了
williem:tom回来了