What is the state initializer pattern?

By Bernie FitzGerald •  Updated: 07/12/23 •  2 min read

In React, the state initializer pattern refers to a technique used to set the initial state of a component. Before the introduction of React hooks, the most common way to initialize state in a React component was through a constructor. However, with the introduction of functional components and hooks, this pattern has become an alternative approach.

The state initializer pattern involves using the useState hook, a built-in hook in React that allows functional components to have state. The useState hook returns an array with two elements: the current state value and a function to update the state.

To initialize the state using this pattern, you can use destructuring assignment to capture the initial state value and the state updater function returned by useState. Here’s an example:

import React, { useState } from 'react';

const MyComponent = () => {
  const [count, setCount] = useState(0);
  // Here, 0 is the initial value for the count state

  // ...

In the example above, the useState hook initialises the count state variable with an initial value of 0. The setCount function can be used to update the state later on. React will re-render the component whenever the state value changes, reflecting the updated state in the user interface.

Using the state initializer pattern with the useState hook, you can manage state within functional components without needing a constructor or a class-based component.

Don’t forget to check out my other React articles here. Thanks for reading!

Bernie FitzGerald

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