Proxy

在目标对象之前架设一层拦截，外界访问该对象时，必须经过这层拦截。

let obj = {
    a: 1
};
const proxy = new Proxy(obj, {
    set: (target, property, value, receiver) => {
        Reflect.set(target, property, value, receiver);
    },
    get: (target, property, receiver) => {
        return Reflect.get(target, property, receiver)
    }
});
console.log(proxy.a);
proxy.b = 2;