readme.md

Usage

In react hooks - for reduce memory consumption

import emptyArr from 'dummyArray';

function myEffect() {
  useEffect(() => {
    // On mount logic
  }, emptyArr);
} 

In props for avoid unnecessary rerenders

import emptyArr from 'dummyArray';

function MyComponent({ list = emptyArr }) {
  return <ul>{list.map(l => <li>{l.text}</li>)}
}

or

import emptyArr from 'dummyArray';

function OtherComponent() {
  const data = useData();
  return <OtherComponent list={data?.list ?? dummyArray} />
}

dummyArray.mjs

class MutationError extends Error {
  message = 'Attempt to mutate empty dummy array';
}

class DummyArr extends Array {
  get length() {
    return 0;
  }

  set length(v) {
    if (v !== 0) throw new MutationError();
  }

  reverse() {
    return this;
  }

  sort() {
    return this;
  }

  pop() {
    return undefined;
  }

  shift() {
    return undefined;
  }

  push() {
    throw new MutationError();
  }

  unshift() {
    throw new MutationError();
  }

  splice() {
    throw new MutationError();
  }
}

export default Object.freeze(new DummyArr());