Javascript代理，如何从目标内部触发陷阱

Question

When creating a proxy in javascript like this

var t = function() {
    self = this;
    this.a = "abc";
    someFunc: function () {
        self.a = "def";
    }
}

target = new t();

var p = New Proxy(target, {
  set: function(){
         //this will never be called when the someFunc changes the a field.
       }
})


p.someFunc();

the set "trap" will never be called I have no problem understanding why this happens, but how should one solve such a situation?

One solution would be to expose the self variale to the outside, and let "someone" change it to the proxy, not very obviouse for anyone using the t object....

Is there any other way? Am I misusing the proxy?

Answer 1

The solution would be not to use self at all:

function T() {
    this.a = "abc";
    this.someFunc = function () {
        this.a = "def"; // `this` in the method (usually) refers to the proxy
    };
}

var p = new Proxy(new T, {
    set: function(target, key, value, receiver) {
        console.log(key, value);
        return Reflect.set(target, key, value, receiver);
    }
});
p.someFunc();

If someFunc does not use the proxy, you cannot force it to without rewriting your T .