What is the `useId` hook in React and when should it be used?

TL;DR

The useId hook in React is used to generate unique IDs for elements within a component. This is particularly useful for accessibility purposes, such as linking form inputs with their labels. It ensures that IDs are unique across the entire application, even if the component is rendered multiple times.

import { useId } from 'react';

function MyComponent() {
  const id = useId();
  return (
    <div>
      <label htmlFor={id}>Name:</label>
      <input id={id} type="text" />
    </div>
  );
}

What is the `useId` hook in React and when should it be used?

Introduction to `useId`

The useId hook is a built-in React hook introduced in React 18. It is designed to generate unique IDs that can be used within a component. This is particularly useful for ensuring that IDs are unique across the entire application, even if the component is rendered multiple times.

When to use `useId`

Accessibility

One of the primary use cases for useId is to improve accessibility. For example, when creating form elements, it is important to link labels to their corresponding inputs using the htmlFor attribute on the label and the id attribute on the input. The useId hook ensures that these IDs are unique, preventing any potential conflicts.

import { useId } from 'react';

function MyComponent() {
  const id = useId();
  return (
    <div>
      <label htmlFor={id}>Name:</label>
      <input id={id} type="text" />
    </div>
  );
}

Dynamic components

When you have components that are rendered dynamically or multiple times, using useId ensures that each instance of the component has a unique ID. This can prevent issues where multiple elements end up with the same ID, which can cause problems with accessibility and JavaScript behavior.

import { useId } from 'react';

function DynamicComponent() {
  const id = useId();
  return (
    <div>
      <label htmlFor={id}>Dynamic Input:</label>
      <input id={id} type="text" />
    </div>
  );
}

function App() {
  return (
    <div>
      <DynamicComponent />
      <DynamicComponent />
    </div>
  );
}

How `useId` works

The useId hook generates a unique string that can be used as an ID. This string is unique across the entire application, ensuring that there are no conflicts even if the component is rendered multiple times. The hook does not take any arguments and returns a string.

import { useId } from 'react';

function ExampleComponent() {
  const id = useId();
  console.log(id); // Outputs a unique ID string
  return <div id={id}>Unique ID Component</div>;
}

Best practices

Use for accessibility: Always use useId when linking labels to inputs to ensure accessibility.
Avoid hardcoding IDs: Instead of hardcoding IDs, use useId to generate them dynamically.
Consistent usage: Use useId consistently across your application to avoid ID conflicts.

What is the `useId` hook in React and when should it be used?

TL;DR