When to Avoid useId Hook in React

The useId hook in React is a highly effective tool for generating unique, stable IDs for accessibility attributes and linking form elements. However, it is not a universal solution for all identification needs in a web application. This article outlines the specific scenarios where you should avoid using the useId hook and explains what you should use instead.

Generating Keys for List Items

You should never use useId to generate the key prop for items in a list. React uses keys to track which items in a list have changed, been added, or been removed. Because useId generates IDs based on the component’s render tree position, reordering a list will cause the generated IDs to shift to different data items. This defeats the purpose of keys, leading to rendering bugs, lost state in input fields, and degraded performance. Instead, always use stable IDs derived directly from your data source, such as database primary keys.

Targeting Elements in CSS Selectors

Avoid using useId if you plan to target those IDs in global CSS stylesheets. The IDs generated by useId contain colons (for example, :r0:), which are special characters in CSS. To target them, you would have to escape the colons in your CSS selectors (e.g., \#\:r0\:), which makes your stylesheets difficult to read and maintain. Furthermore, because these IDs are generated dynamically based on render order, they are not guaranteed to remain identical if the layout of your application changes. Use static, semantic class names for styling instead.

Querying Elements in Automated E2E Tests

Do not rely on useId for locating elements in end-to-end (E2E) testing frameworks like Cypress, Selenium, or Playwright. Since the generated IDs depend on the order in which React components are mounted, adding or removing a component elsewhere on the page can shift the IDs of unrelated elements. This makes your automated tests fragile and prone to random failures. For testing purposes, it is best to use stable, dedicated attributes like data-testid.

Creating Database Keys or Security Tokens

The useId hook is designed solely for client-side and server-side DOM linking. The generated strings are not cryptographically secure, nor are they globally unique across different user sessions or application instances. You should never use useId to generate unique identifiers for database records, API request tokens, or security salts. For these use cases, utilize robust UUID libraries or cryptographically secure random number generators.

Simple, Single-Instance Static Elements

If a component is static and guaranteed to only ever render once on a single page, using useId introduces unnecessary overhead. For a single contact form or a search bar that has no chance of being duplicated on the page, hardcoded, descriptive string IDs (like id="main-search-input") are cleaner, easier to debug, and more performant.