Common techniques for working with immutable data in Redux?

Immutable data is a fundamental concept in Redux. By ensuring that state changes are immutable, Redux helps to maintain a predictable state tree and simplifies debugging by enabling easier tracking of changes.

In this article, we’ll see the following techniques and best practices for working with immutable data in Redux.

1. Spread Operator for Object and Array Immutability

The spread operator (`…`) is a concise way to create shallow copies of objects and arrays, preserving the original data while making modifications. When updating the state, you should always create a new copy of the state object or array rather than mutating the original.

Syntax:

// Updating an object immutably
const newState = { ...prevState, key: 'new value' };
// Updating an array immutably
const newArray = [...prevArray, 'new item'];

Example:

Javascript

// Original state
const prevState = {
    key1: 'value1',
    key2: 'value2'
};

// Updating an object immutably using spread operator
const newState = { ...prevState, key2: 'new value' };

console.log(newState);

Output:

{
    key1: 'value1',
    key2: 'new value'
}

2. Object.assign() for Object Immutability

Another way to make new objects in JavaScript is by using Object.assign(). It lets you combine different objects together into a new one, without changing the original objects. This helps keep your data safe and unchangeable.

Syntax:

// Updating an object immutably with Object.assign()
const newState = Object.assign({}, prevState, { key: 'new value' });

Example:

Javascript

// Original state
const prevState = {
    key1: 'value1',
    key2: 'value2'
};

// Updating an object immutably using Object.assign()
const newState = Object.assign({}, prevState, { key2: 'new value' });

console.log(newState);

Output:

{
    key1: 'value1',
    key2: 'new value'
}

3. Array.slice() and Array.concat() for Array Immutability

`Array.slice()` returns a shallow copy of a portion of an array, while `Array.concat()` joins two or more arrays and returns a new array. Both methods are useful for immutably updating arrays.

Syntax:

// Updating an array immutably with Array.slice()
const newArray = prevArray.slice().concat('new item');
// Another way to update an array immutably with Array.concat()
const newArray = prevArray.concat('new item');

Example:

Javascript

// Original array
const prevArray = ['item1', 'item2', 'item3'];

// Updating an array immutably using Array.slice() and Array.concat()
const newArray = prevArray.slice().concat('new item');

console.log(newArray);

Output:

['item1', 'item2', 'item3', 'new item']

Conclusion

Keeping data from changing in Redux is really important for making sure everything works as expected in your app. Using tools like the spread operator, Object.assign(), and Array.slice(), you can handle data in a way that keeps it safe and unchangeable. Using these techniques not only makes your code better but also makes your app faster and easier to manage, especially in big JavaScript apps.