andreypopp/autobind-decorator

If bound methods or fields are re-assigned, they become shared between instances

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#76 opened on Nov 16, 2018

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Description

If bound methods or fields are re-assigned, they become shared between instances

Found this issue while trying to debounce bound method

Below test will fail

class A {
  @boundMethod
  bound() {}
}

const a = new A();
const b = new A();
a.bound = {
  foo: 'bar'
};
assert.notEqual(a.bound, b.bound);

Contributor guide

Tech stack
javascript
Domain
developer experiencetesting
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
JavaScript class syntaxDecorator patternAutobinding
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65
Research direction
The bug occurs when a bound method or field is reassigned on an instance, causing shared state across instances. To fix, examine the existing implementation of the boundMethod decorator (likely in src/index.js or similar). The test case provided in the issue description should be added to the test suite. A potential solution is to generate a new binding function or use a WeakMap to store original values per instance. See the issue comments for discussion on possible approaches, but no PRs are linked.