rosma

Rosma

Simple and easy-to-use global state management for React. no need for provider, reducer or nothing else!

Installation

npm i rosma

Documentation

https://rosma.dev/

Counter app

import { useObserver } from 'rosma';

export default function Counter() {
  const { count, setCount } = useObserver(0);

  return <button onClick={() => setCount(count + 1)}>{count}</button>;
}

No order for variables

import { useObserver } from 'rosma';

export default function Counter() {
  const { setCount, count } = useObserver(0);

  return <button onClick={() => setCount(count + 1)}>{count}</button>;
}

The only concept that must be notice is that you must add a 'set' to the beginning of the setter name of the destructed variable.

For example if you want a setter method for the 'count' variable, you should name that setter as 'setCount'.

Also, all the destructed variables are case insensitive

import { useObserver } from 'rosma';

export default function Counter() {
  const { CouNt, setcOunT } = useObserver(0);

  return <button onClick={() => setcOunT(Count + 1)}>{CouNt}</button>;
}

Multiple destructuring

Destruct all the variables you want at once

import { useObserver } from 'rosma';

export default function Counts() {
  const { count, setCount, count1, setCount1 } = useObserver(0);

  return (
    <>
      <button onClick={() => setCount(count + 1)}>{count}</button>
      <button onClick={() => setCount1(count1 + 1)}>{count1}</button>
    </>
  );
}

Different initial values

In the example above, all the variables take the initial value of 0. to avoid this, one of the following methods can be used:

• Define the initial values separately

import { useObserver } from 'rosma';

export default function Counts() {
  const { count, setCount } = useObserver(10);
  const { count1, setCount1 } = useObserver(20);

  return (
    <>
      <button onClick={() => setCount(count + 1)}>{count}</button>
      <button onClick={() => setCount1(count1 + 1)}>{count1}</button>
    </>
  );
}

• Define the initial values at once

If you want to set the initial values and also destruct them at once, you can set the initial values directly from the observer.

import { observer, useObserver } from 'rosma';

observer.set({ count: 10, count1: 20 });

export default function Counts() {
  const { count, setCount, count1, setCount1 } = useObserver();

  return (
    <>
      <button onClick={() => setCount(count + 1)}>{count}</button>
      <button onClick={() => setCount1(count1 + 1)}>{count1}</button>
    </>
  );
}

Notes app

import { useObserver } from 'rosma';

export default function Note() {
  const { note = '', setNote, notes = [], setNotes } = useObserver();

  return (
    <>
      <input value={note} onChange={(e) => setNote(e.target.value)} placeholder="write something" />
      <button
        onClick={() => {
          setNotes(notes.concat(note));
          setNote('');
        }}
      >
        Add
      </button>
      <ul>
        {notes.map((note, index) => (
          <li key={index}>{note}</li>
        ))}
      </ul>
    </>
  );
}

Avoiding extra rerender

If you want the entire main component not to be re-rendered with state changes, you can easily split the elements of the main component into smaller components using the withState method.

import { withState } from 'rosma';

const Input = withState(({ note = '', setNote }) => <input value={note} onChange={(e) => setNote(e.target.value)} placeholder="write something" />);

const Button = withState(({ note, setNotes, setNote }) => (
  <button
    onClick={() => {
      setNotes((notes = []) => notes.concat(note));
      setNote('');
    }}
  >
    Add
  </button>
));

const List = withState(({ notes = [] }) => (
  <ul>
    {notes.map((note, index) => (
      <li key={index}>{note}</li>
    ))}
  </ul>
));

export default function Note() {
  return (
    <>
      <Input />
      <Button />
      <List />
    </>
  );
}

Further optimization

To avoid extra rendering, you can read the values directly from the observer. In the example above, the Button component is re-rendered every time that the 'note' variable is changed. But you can avoid this extra rendering by reading the 'note' value from the observer.

import { observer, withState } from 'rosma';

const Input = withState(({ note = '', setNote }) => <input value={note} onChange={(e) => setNote(e.target.value)} placeholder="write something" />);

const Button = withState(({ setNotes, setNote }) => (
  <button
    onClick={() => {
      setNotes((notes = []) => notes.concat(observer.get('note')));
      setNote('');
    }}
  >
    Add
  </button>
));

const List = withState(({ notes = [] }) => (
  <ul>
    {notes.map((note, index) => (
      <li key={index}>{note}</li>
    ))}
  </ul>
));

export default function Note() {
  return (
    <>
      <Input />
      <Button />
      <List />
    </>
  );
}