Questions tagged [javascript-proxy]
36 questions
0
votes
1 answer
Typescript: function should return proxy object of generic object type
The following function should create a proxy object with a specific handler, but typescript is throwing a type error when I try it that way.
function createProxiedObject(obj: T): T {
const handler = {
set(obj: {[key:…
Arber
- 421
- 1
- 3
- 13
0
votes
1 answer
Value of this inside a Proxy trap
I have the following code:
function delay(f, ms) {
return new Proxy(f, {
apply(target, thisArg, args) {
console.log(this)
console.log(thisArg)
setTimeout(() => f.apply(thisArg, args), ms)
}
…
Pavlo Zalutskiy
- 11
- 2
0
votes
0 answers
JavaScript Error: caught (in promise) TypeError: 'set' on proxy: trap returned falsish for property
I'm attempting to add an "eventlistener" of sorts to trigger when all of the application resources have completed loading. If I understand Proxies correctly, "this is the way" to monitor object property changes. The following code works in my…
TK421
- 801
- 5
- 16
- 24
0
votes
1 answer
TypeScript types for Proxy with dynamic properties
I want to type a JavaScript Proxy that allows access to arbitrary properties. A contrived example, an object that maps every property to it's own property name:
const proxy = new Proxy({}, {
get(target, property) {
return prop;
…
tlrobinson
- 2,812
- 1
- 33
- 35
0
votes
0 answers
React - Use JavaScript Proxy Object to update with Custom Hook
I am seeing a weird behavior with a simple custom React Hook I am trying to come up with. Any ideas on why it's not working as intended would be greatly appreciated.
So I have a custom hook called useProxyState.
import { useState } from…
Hunter Woodall
- 1
- 3
0
votes
0 answers
Javascript Proxy Object in React Custom Hook
I have 2 custom hooks useFormInput and other useFormInputWithoutProxies which is using Javascript proxy
My Question what benefit does Javascript proxy provides over creating normal custom hooks ?
Can Somebody give real world use case or example as…
Sachin
- 149
- 1
- 16
0
votes
1 answer
How to make a web component return a Proxy (and be extended)
The goal is to have a base class A extending HTMLElement that customizes getters and setters. Then class B would extend class A and do stuff.
The way to do this is by wrapping class A with a proxy (not the instance, but the class) so B can extend…
daniel p
- 741
- 7
- 12
0
votes
0 answers
Proxy js object: where are defined arguments when calling a function using Reflect.get()
Trying to understand the internals of Proxy and Reflect built-in objects, I've reached - IMO - an interesting "how does this even work" point:
Let's say I want to wrap into a Proxy this object and detect when we're accessing a callable…
Manu Artero
- 9,238
- 6
- 58
- 73
0
votes
2 answers
Get array in [[target]] from proxy
How can i get this number from productCount.value (screenshot)?
Trying productCount.value.array, but i will get again proxy - [[target]] - array
Edit 1:
If i use productCount.value.array[0] i will get error Invalid value used as weak map key
Jessika
- 31
- 8
0
votes
0 answers
In Javascript, is it possible to proxy 'this' within a constructor, without editing the constructor
Imagine I have the following Javascript class:
class C {
constructor() {
this.foo = "bar"
}
}
I have proxied C so I can intercept construction of C:
const handler = {
construct(target, args, newTarget) {
...
}
}
I need to find a…
ebdavis
- 105
- 8
0
votes
1 answer
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: function (target) {
return…
Melab
- 2,594
- 7
- 30
- 51
0
votes
1 answer
Extend JavaScript (Vuejs3) proxies with another method
Vue3 uses proxies to wrap object data properties.
I have several of these objects where I'd like to add additional functionality to the proxy itself, namely watch get for certain scenarios. Is there a way to extend the proxy object created by Vue,…
Randy Hall
- 7,716
- 16
- 73
- 151
0
votes
1 answer
Iterating over a Proxy in Vue Composition API
I have a computed value emptyRowsRemoved derived from the Reactivity API. I need to iterate over this value. But because computed() returns a proxy, I am no longer able to iterate over it with a .forEach.
I was curious, is the only way to iterate…
Alan
- 1,067
- 1
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0
votes
1 answer
How do I intercept sort function within a JS proxy with a function?
My previous related question: How do I intercept sort function within a JS proxy?
Given the proxy:
function sort(customSort) {
/* Write logs */
console.log("Intercepted sort")
return this.sort(customSort);
}
function get( target, prop,…
Blue Granny
- 772
- 1
- 8
- 24
0
votes
1 answer
Passing Proxy object as thisArgument to apply throws TypeError: Illegal Invocation
I'm trying to trap calls to Storage. As far as I can tell there are two ways to call either setItem or getItem:
sessionStorage.setItem("foo", "bar");
let item = sessionStorage.getItem("foo");
…
Mark J Miller
- 4,751
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- 74