Sentry Answers>React>

How do I Conditionally add Attributes to React Components?

How do I Conditionally add Attributes to React Components?

Matthew C.

The Problem

You have an attribute or property that you would like to conditionally add to your component or element. How do you do this?

Let’s say that we have a submit button that we would like to disable if a particular checkbox, such as a checkbox asking the user if they’ve read the terms of service, has not been checked.

The Solution

There are different ways to conditionally add attributes to components. The method you choose to use depends on personal or team preferences and how many attributes you want to conditionally render. The methods used, apart from the spread operator, can also be used for conditionally rendering components.

A React component tree is made up of host and non-host components. Host components are platform-specific. In a browser, a React element that renders an <input> DOM element is a host component. If a React host component attribute is set to null, undefined, or false, React will not pass the attribute to the DOM element. This is not true for non-host React components, such as a custom component that you define. In the example code below, if the checked state is false, the button will be disabled:

Click to Copy
<label> <input type="checkbox" checked={checked} onChange={handleChange} /> I have read the terms of service </label> <button type="submit" disabled={!checked}> Submit </button>

Using a Boolean Value

You can use a Boolean value to conditionally add an attribute to an element:

Click to Copy
<button type="submit" disabled={!checked}> Submit </button>

You can also cast values to a Boolean using the Boolean() function or the double NOT (!!) operator.

Using the Logical AND (&&) Operator

You can use the logical AND (&&) operator to conditionally add an attribute to an element based on the output of a logical AND expression:

Click to Copy
<button type="submit" disabled={state.type === 'guest' && !checked}> Submit </button>

Using the Conditional (Ternary) Operator

You can use a ternary operator to conditionally add an attribute to an element based on the output of a ternary expression:

Click to Copy
<button type="submit" disabled={!checked} className={checked ? 'btn-enabled' : 'btn-disabled'}> Submit </button>

This is similar to using the logical AND (&&) operator. It takes a little longer to type but some programmers may find it more readable.

Using an If Statement

You can use an if statement to alter attributes if certain conditions are met, such as in the example code below:

Click to Copy
let disabled = false; if (state.type === "guest" && !checked) { disabled = true; } return ( ... <button type="submit" disabled={disabled}> Submit </button> );

Using Spread Syntax

You can use spread syntax to add multiple attributes at once. This is useful if you have many attributes that you want to add to an element or component. In the example code below, the <input> attributes are in an object. These are then conditionally changed using an if statement before spreading in the attributes to an element during rendering.

Click to Copy
const attributes = { type: "checkbox", name: "terms", id: "terms" }; if (state.type === "guest") { attributes.required = false; attributes.disabled = true; } return ( ... <input {...attributes} /> );
  • Sentry BlogHow to identify fetch waterfalls in React
  • Syntax.fmReact Server Components
  • Syntax.fmWhy the jQuery Creator Uses React and Typescript
  • Syntax.fmListen to the Syntax Podcast
  • Sentry BlogReact Native Debugging and Error Tracking During App Development
  • Syntax.fmDiscussion on building native iOS and Android apps with React Native
  • SentryReact Error & Performance Monitoring
  • Sentry BlogFixing memoization-breaking re-renders in React
  • Syntax.fm logo
    Listen to the Syntax Podcast

    Tasty treats for web developers brought to you by Sentry. Get tips and tricks from Wes Bos and Scott Tolinski.

    SEE EPISODES

Considered “not bad” by 4 million developers and more than 100,000 organizations worldwide, Sentry provides code-level observability to many of the world’s best-known companies like Disney, Peloton, Cloudflare, Eventbrite, Slack, Supercell, and Rockstar Games. Each month we process billions of exceptions from the most popular products on the internet.

© 2024 • Sentry is a registered Trademark
of Functional Software, Inc.