var test = {
_age : 0,
methods:function(a)
{

console.log("发生变化了值为:"+a);

},
//_Age reading and writing
set age(age) {

if(age!=this._age)
{
    this.methods(age);
    this._age = age;
}}, 

get age() {return this._age;}
};
You can use the set and get methods of the object to perform the desired results

Cannot be implemented directly.
But it can be achieved in other ways.

var obj = {
        set: function (key, value) {
            if(['set', 'change'].indexOf(key) > -1) return;

            this[key] = value;

            this.change();
        },

    };

    obj.change = function(){
        alert(1)
        console.log(this);
    }

    obj.set('name', 'segmentfault');
    
     // 将你需要的变量设为obj的一个属性
     // 更改变量用obj.set()这个方法

js set/get
You can add your logic code in the set method, so that your code will be triggered every time it is modified