SOURCE

/* 单例模式 */


let _instance = function(fn){
   var instance 
   return function(){
        if(!instance){
            console.log('第一次')
            instance= fn.apply(this, arguments)
        }
        return instance
    }
}


let a =function(){
    return {
        a:1
    }
}



let dd = _instance(a)

let fc = dd()

let fcc = dd()

console.log(fc,fcc,fc==fcc)