Questions tagged [es6-proxy]
The ES2015 Proxy object allows the creation of objects with custom dispatch semantics for operations like property lookup, assignment, enumeration, invocation as a function or constructor.
es6-proxy
308
questions
0
votes
0
answers
26
views
I am trying to work with ES6 Proxies but am noticing something super weird, it is getting called twice [closed]
I am trying to implement a simple backbone model which has handlers for change and delete events on the model. The change handler for changing the value of a property gets executed 2 times instead of ...
- 28.1k
0
votes
1
answer
279
views
Can't redirect target of freeze operation via preventExtensions trap
Code:
(function () {
"use strict";
var proxy;
var realTarget;
var target;
realTarget = {};
target = {};
proxy = new Proxy(target, {
isExtensible: ...
- 18.2k
0
votes
1
answer
30
views
Multiple Access to two-dimensional array (using setters/getter via Proxy or Object.defineProperty)
I have a two dimensional array that I need to perform read and write action on from various angles.
Sometimes I need to get/set a single row (easy of course) and sometimes I need to get/set a single ...
- 6,003
22
votes
3
answers
50k
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how to get an array out of a javascript proxy
I was wondering how to get an array out of a proxy's target value in JavaScript. I have something like this :
Proxy :
[[target]] : Array // the array I need to extract
[[handler]] : Object
[[...
0
votes
1
answer
65
views
Detect direct instances in JavaScript
A couple of years ago, I wanted figure how to create a type check for class A that returns true only for objects instantiated by new A(). For this, I wrote the class like this:
class A {
static #...
- 19.4k
18
votes
5
answers
5k
views
Major use cases for ES6 proxies
I recently got to know about ES6 proxies but I don't see a good reason to use it. I mean, everything that one could do with Proxy can be done without it, except if I'm missing something.
For example,...
- 27.5k
-1
votes
1
answer
95
views
Why is this object a Proxy only when the page field is 1?
Steps to reproduce:
Open the reproduction
Open the browser console
When the project starts it will errors with:
Uncaught (in promise) DOMException: Failed to execute 'put' on 'IDBObjectStore': #<...
- 7,141
2
votes
0
answers
161
views
Can a proxy with a non-function target be invoked like a function?
Per my answer to this question, chrome allows you to do the following (chrome 49):
class Person {
constructor() {
this.fn = function(a) { this.a = a; };
return new Proxy(this, {
apply: ...
- 27.5k
5
votes
1
answer
595
views
What would be a use case for identity-preserving membrane proxies?
When I was reading about ES6 Proxies, it seemed simple enough to understand until I had taken a look at this example.
I'm stumped. I don't understand the "wet/dry" terminology that they use, ...
- 27.5k
29
votes
2
answers
20k
views
How can I modify a constructor so that it return a proxy that prevents adding new properties to the object?
I want user to only set specific properties to an object but as the same time that object should be constructed from custom class.
For example
var row = new Row({
name : 'John Doe',
email : '...
- 27.5k
0
votes
1
answer
339
views
Why can’t a proxy trap invoke Function.prototype.apply to construct an ES6 class?
I'm trying to Proxy a ES6 constructor (mostly trying to emulate Python's descriptors for fun and learning):
class _Record {
constructor(data) {
this._data = data;
}
}
const ...
- 27.5k
3
votes
1
answer
263
views
How do I intercept sort function within a JS proxy?
I know how to intercept get`set` and such within a proxy using the following code:
function get( target, prop, receiver ) {
console.log("Intercepted get")
return Reflect.get( target, ...
- 27.5k
23
votes
3
answers
15k
views
Can Babel transpile code using Proxy into ES5?
I'm using babelify version 6.3.0 set to stage 0. ES6 / ES7 are working great. However when I try to use JavaScript's proxy functionality:
set product(product={}) {
this._product = new Proxy({}, {})...
- 27.5k
0
votes
1
answer
79
views
Why are proxy traps not invoked for instances constructed from a proxied constructor?
I'm trying to register function change via proxies with this code:
const handler = {
construct(objTarget, args, oldConstructor) {
return new objTarget(...args)
},
set(target, key, value) {
...
- 27.5k
1
vote
1
answer
66
views
JavaScript Proxy not working for opened Window object
I need to Proxy a window object opened with window.open.
So far as I understand it (which is not well), the trivial "handler" here should effectively be the identity operation, passing thru ...
- 19.4k