JavaScript Proxies: set does not trigger when modifying objects in an array

Question

I have an array filled with objects

let array_of_objects = [{
  id: 1,
  name: "John"
}, {
  id: 2,
  name: "Bill"
}, {
  id: 3,
  name: "Mike"
}];

I then create a proxy with a set handler and my array as a target

let p = new Proxy(array_of_objects, {
  set: function(target, property, value) {
    //Do something
  })
})

If I call forEach on the proxy:

p.forEach((e) => {
  e.name = "some new value";
});

The set trap of my proxy does not trigger. Whereas manipulating the array (p.push() etc.). Does.

What trap should be used in my case?

madox2 · Accepted Answer · 2016-05-18 09:44:23Z

2

You need to create proxy for each object you want to modify. For example you can map your array to wrap each object with proxy:

const p = array_of_objects.map(e => new Proxy(e, {
  set: function(target, property, value, receiver) {
    console.log(target, property, value, receiver)
    // Do something
  }
}));

p.forEach(e => {
    e.name = "some new value";
});

edited May 18, 2016 at 9:44

answered May 18, 2016 at 9:38

madox2

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