Features

☢ Deeply Reactive, Directly Mutate State at any level to Update Component

⚡ Blazing Fast - 25% faster than useState

📺 No Extra Re-Renders - Auto Mutation batching

🌿 Always Fresh State, unlike useState

🧬 Reactive Bindings For Inputs

⚛ Reactive Props

☕ Zero Dependencies, Ultra Light-Weight < 1kb

🌻 Motivation

While the React's useState hook has been great for simple states, it is still a pain to update a complex state.

It also comes with other problems like not having the access to fresh state right away after the new state is set and closure problems because of state's value only updating after a re-render.

We can eliminate these problems, Improve performance and Introduce exciting new features in React with a Truly Reactive State !

Enter radioactive-state

Installation

npm i radioactive-state

☢️ What's a Radioactive-State ?

Radioactive state is a deeply reactive state. When it is mutated at any level ( shallow or deep ) it re-renders the component automatically !

No need to set the state. No need to use libraries like immer.js to produce a new state. No overhead of creating a new state at all! Just mutate your state, that's it !

✨ Creating a Radioactive State With useRS hook

radioactive-state gives you a hook useRS (use radioactive state) which lets you create a radioactive state in your React Components.

Examples

Click on the triangle icon to expand the Example

Live Demo

import useRS from 'radioactive-state';

const Counter = () => {
  // create a radioactive state
  const state = useRS({
    count: 0,
  });

  // yep, that's it
  const increment = () => state.count++;

  return <div onClick={increment}>{state.count}</div>;
};

Let's take this a step further, Let's make an app that has an array of counters, each of them can be incremented individually and sum of all the counters is displayed too

This examples shows that deep mutation also triggers a re-render and that you can use any mutative functions directly

Live Demo

import useRS from "radioactive-state";

const Counters = () => {

  const state = useRS({
    counts: [0],
    sum: 0
  });

  const increment = (i) => {
    state.counts[i]++;
    state.sum++;
  };

  const addCounter = () => state.counts.push(0);

  return (
    <>
      <button onClick={addCounter}> Add Counter </button>
      <div className="counts">
        {state.counts.map((count, i) => (
          <div className="count" onClick={() => increment(i)} key={i}>
            {count}
          </div>
        ))}
      </div>
      <div className="count sum">{state.sum}</div>
    </>
  );
};

📺 No Extra Re-Renders, Mutations are Batched

You might be wondering:

"What if I mutate multiple keys in state, Is that going to trigger a re-render component multiple times ?"

Nope! 😉

Example:

// suppose you are mutating multiple things in your state in a function doStuff

const doStuff = () => {
  state.a = 200;
  state.b.x.y.push([10, 20, 30]);
  state.c++;
  state.c++;
  state.c++;
  delete state.d.e.f;
  state.e.splice(10, 1);
  state.f = state.f.filter(x => x.completed);
};

// When this function is called
// it is not **not** going to trigger re-render of component 8 times 😉
// it will only trigger re-render 1 time! - No extra re-renders! 🤗

How is that possible ?

Mutations are batched into a one single mutation. So, No matter how many times you mutate the state, it only triggers re-render once

This allows you to perform a complex mutation in multiple steps without having to worry about re-renders

const addNewFriend = (newFriendID) => {
  const {users, userID} = state
  const user = users[userID]
  const newFriend = users[newFriendID]
  user.friends.push(newFriendID)
  newFriend.friends.push(userID)
}

⚛ Reactive Props

In traditional React, Props are considered immutable and mutating them does not trigger re-render. But When using radioactive-state, if you pass a piece of state as a prop to child component, this child component has the capability to trigger a re-render in parent component by mutating the prop !

This can be a powerful feature, where you no longer have to pass functions as props to child component for triggering a re-render in parent component, which also removes the need to memoize that function

Example: Todos App

Live Demo

🌿 State is always fresh !

Unlike useState, useRS's state is always fresh

What does that mean ?

When you set a new state using useState's setter function, it does not directly change the value of state. value of state is changed only after a re-render. This can cause some weird bugs.

Let's see those problems and see how radioactive-state is immune to them.

Live Demo

const [count, setCount] = useState(0)

const increment = () => {
  console.log('before: ', count)
  setCount(count + 1)
  console.log('after: ', count)
}

// when increment is called, you would get this logs:
// before: 0
// after: 0

// same thing happens no matter what data type you are using - reference type or value type

useRS solves it !

useRS's state is mutated directly by the user. So, No need to wait for a re-render to get the fresh state.

Live Demo

const state = useRS({
    count: 0
  })

const increment = () => {
  console.log('before: ', state.count)
  state.count++
  console.log('after: ', state.count)
}

// works as expected 😄
// before: 0
// after: 1

With radioactive-state, You can use your state with confidence that whenever you use it, it's gonna be fresh ! 😙

Let's assume that increment function is async and before incrementing the value of count, we have to wait for some async task.

Now guess what happens if you click the counter quickly 3 times? count is only going to increment to 1 instead of 3, even though increment function is called 3 times !

Live Demo

const [count, setCount] = useState(0)

const increment = async () => {
  await someAsyncTask(); // assume that this takes about 500ms
  setCount(count + 1) // does not work properly
}

This happens because setCount keeps using old value of count until the component re-renders. This is because increment function "closes over" the count when it was defined.

To fix this issue, you update the state using a function like this:

setCount(previousCount => previousCount + 1)

This gets awkward when you want to update other states based new value of this state.

useRS does not have this problem !

Live Demo

If you click the button 3 times quickly, count will only increment from 0 to 3 after 500ms. It works as expected 🙌

const state = useRS({
  count: 0
})

const increment = async () => {
  await someAsyncTask(); // assume that this takes about 500ms
  state.count++ // works ! 😙
}

⚡ Radioactive State is blazing fast !

useRS is 25% faster than useState for an a fairly Complex React App.

This number is derived from an average of 100 performance tests where an array of 200 objects is rendered and various operations like adding, removing, re-ordering and mutations were done one after another.

Note that, useRS keeps getting faster and faster compared to useState if you keep increasing the complexity of state, even more than 25% But, for a simple web app, both will have about the same performance where state of a component is not that complex.

Why useRS is faster than useState ?

In the case of useState, every time you want to update the state, you have to create a new state and call setter function with the new state.

But, In the case of radioactive-state you don't have to create a new state, you just mutate the state and that's it. radioactive-state does not create a new state under the hood either. There are other optimizations as well, which makes sure no extra work is done, no extra re-renders are triggered.

🧬 Reactive bindings for inputs

using the useState

const [input, setInput] = useState("type something");

<input
  value={input}
  onChange={(e) => setInput(e.target.value)}
  type='text'
/>

using the useRS

// creating state
const state = useRS({
  input: ''
})

<input
  value={state.input}
  onChange={(e) => state.input = e.target.value}
  type='text'
/>

Both are fairly easy but becomes annoying if you have a form with multiple inputs

You would also have to convert string to number if the input is type 'number' or 'range'. You would also need to use 'checked' prop instead of 'value' for checkboxes and radios

Radioactive State provides a binding API that lets you bind an input's value to a key in state.

To bind state.key to an input you prefix the key with $ - state.$key and then spread over the input. that's it ! 😮

<input {...state.$key}  />

This works because, state.key returns the value but state.$key returns an object containing value and onChange props, which we are spreading over input

Bindings takes care of different types of inputs

Bindings rely on initial value of the key in state to figure out what type of input it is

if the initial value is a type of string or number, state.$key returns object containing value and onChange

If the initial value is type of boolean, state.$key returns an object containing checked and onChange props and uses e.target.checked internally in the onChange function

If the initial value type of number, onChange function converts the e.target.value from string to number then saves it in the key.

Example

Live Demo

const state = useRS({
  a: 69,
  b: 420,
  c: "Hello",
  d: "Write something here",
  e: true,
  f: "bar"
});

const { $a, $b, $c, $d, $e, $f } = state;

return (
  <div className="App">
    <pre> {JSON.stringify(state, null, 2)}</pre>
    <input {...$a} type="number" />
    <input {...$b} type="range" min="0" max="1000" />
    <input {...$c} type="text" />
    <textarea {...$d} />
    <input {...$e} type="checkbox" />
    <select {...$f}>
      <option value="foo"> foo </option>
      <option value="bar"> bar </option>
      <option value="baz"> baz </option>
    </select>
  </div>
);

Dealing with expensive initial State

If initial State is a result of doing some expensive calculation, (for example, getting the initial State from localStorage), It would be very inefficient to directly call it like this

const state = useRS({
  x: getX(); // assume that getX is an expensive function
})

This is inefficient because getX runs every time the component renders. This is not what we want. We just want to call getX only once to get the initial state.

To fix this you can just pass the function as initial State, without calling it. This is similar to what we do in useState

useState

const [x, setX] = useState(getX)

useRS

const state = useRS({
  x: getX
})

This is valid for entire state tree as well

// assume that getState function when called returns the initial State

const state = useRS(getState)

This also valid for any deeply nested key in the state tree

// assume that getD is a function which when called returns the initial value of d

const state = useRS({
  a: 100
  b: {
    c: {
      d: getD
    }
  }
})

⛳ Mutation flag

If we mutate a reference type data in state such as array or an object, it's reference stays the same. This can create problems If you want to run some effect when it is mutated.

Example

const state = useRS({
  todos: []
})

// when addTodo is called, it would trigger a re-render
// but the effect would not run because todos is mutated, its reference is same
useEffect( () => {
  console.log('todos changed to', state.todos)
}, [state.todos])


const addTodo = (todo) => state.todos.push(todo)

This happens because useEffect uses === to check whether the dependencies changed or not. To fix this, instead of adding state.todos in dependency array add state.todos.$

state.key.$

state.key.$ is a number which is increment by some amount when key is mutated. So, state.key.$ works a mutation flag for state.key

Example

const state = useRS( { todos: [] })

useEffect( () => {
  console.log('todos changed to', state.todos) // works !
}, [state.todos.$]) // eslint-disable-line

If you have ESlint setup, it will complain about not adding state.todos in the dependency array. You can fix it by disabling eslint for that particular line.

Note that this is only necessary of reference type data, don't do this for value types such as number, strings, boolean etc. because value types are immutable and they are re-assigned a new value, they are not mutated.

const state = useRS({
  count: 0
})

// works
useEffect( () => {
  console.log('count changed to', state.count)
}, [state.count])

// count is actually assigned a new value, it is not mutated
// count++ is count = count + 1
const increment = () => state.count++

❓ FAQs

Yes. You don't have to put all of the state of the component inside the state object. You can use the hook more than once.

Example

const todos = useRS([])
const form = useRS({
  name: '',
  age: 0,
})

While this is okay, I would advise you to not do this, Because putting all of state in one object gives you *better performance in the case of radioactive-state. (because of better mutation batching)

It would also be hard to store simple value types, because simple value types can not be mutated and so you would need to wrap it inside an object.

Example

const count = useRS(0) // invalid, gives error ❌

const count = useRS( { value: 0 }) // works ✅

This would also make creating reactive bindings awkward. That's why it is strongly recommended to store all the state into a single object by using useRS only once !

💙 Contributing

PR's are welcome !

Found a Bug ? Create an Issue.

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👨‍💻 Author

Manan Tank

Twitter

🍁 Licence

ISC