How to Implement useId Hook in React

This article provides a straightforward guide on how to implement the useId hook in React. You will learn what the useId hook is, why it is essential for generating unique, stable IDs for accessibility attributes, and how to apply it in your React components with practical code examples.

What is the useId Hook?

Introduced in React 18, useId is a built-in React hook used to generate unique IDs that are stable across both the server and the client.

Before useId, developers often used Math.random() or global counters to generate IDs for HTML elements. However, these methods caused hydration mismatches during Server-Side Rendering (SSR) because the ID generated on the server did not match the ID generated on the client. The useId hook solves this problem by ensuring the generated IDs are consistent across server and client renders.

Basic Implementation

To use the useId hook, import it from the 'react' package and call it inside your functional component.

Here is a basic example of using useId to link an HTML <label> to an <input> element:

import { useId } from 'react';

function LoginForm() {
  const emailInputId = useId();

  return (
    <form>
      <label htmlFor={emailInputId}>Email Address:</label>
      <input id={emailInputId} type="email" name="email" />
    </form>
  );
}

In this example, useId generates a unique string identifier. Assigning this string to both the htmlFor attribute of the label and the id attribute of the input ensures the form is fully accessible to screen readers.

You do not need to call useId multiple times if you have several related elements within the same component. Instead, you can call useId once and append a unique suffix to the generated ID for each element. This keeps your code clean and performant.

import { useId } from 'react';

function RegistrationForm() {
  const baseId = useId();

  return (
    <form>
      <div>
        <label htmlFor={`${baseId}-firstName`}>First Name:</label>
        <input id={`${baseId}-firstName`} type="text" />
      </div>
      <div>
        <label htmlFor={`${baseId}-lastName`}>Last Name:</label>
        <input id={`${baseId}-lastName`} type="text" />
      </div>
    </form>
  );
}

When Not to Use useId

While useId is highly effective for accessibility-related attributes, there are specific scenarios where it should not be used: