const a={
_b:5,
};
Object.defineProperty(a,'c',{
get:function(){
console.log('?');
this._b=this._b-1
return this._b;
},
set:function(newValue){
console.log('#');
return this._b=newValue;
}
})
!function(){
console.log(a.c) //3
a.c=10;
console.log(a.c) //3
}();