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Error Handling in React 16 | The Ultimate Guide

Navdeep Singh Gill | 18 January 2022

Error Handling in React 16 | Ultimate Guide

What is Error Handling?

The response and recovery methods from erroneous situations contained in a software application are error handling. It's the process of anticipating, identifying, and addressing application, programming, and communication difficulties, to put it another way. Error management aids in the continuation of the program's usual flow. When it comes to error-handling solutions, many applications confront several design issues.

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Errors are divided into three categories

Errors in logic

Errors that occur during compilation

Errors during execution

Rigorous proofreading is one of the error-handling approaches for development errors. The most common error-handling strategies for logic errors or faults are diligent application debugging or troubleshooting. Depending on the circumstances, error-handling apps can correct runtime issues or reduce their impact by implementing suitable counter measures. Most hardware applications provide an error-handling mechanism that allows them to recover from unforeseen faults gracefully.

Error handling is critical for application designers, and developers, independent of the application built or programming languages utilized because errors can be disastrous. In the worst-case situation, the application's error handling procedures force the user to log out and the system to shut down.

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What are the Error Boundaries?

React 16 presented a new concept of an “error boundary” to solve a problem when a part in the UI contains a JavaScript error. It shouldn’t damage the whole application. Error Boundaries are React components used to manage JavaScript errors in their child component tree, and they give some form of boundaries or checks on errors.

React components that log and display a fallback user interface in the event of a JavaScript failure anywhere in their child component tree. It looks for problems in rendering, lifecycle methods, and other areas. Errors which Error Boundaries won’t catch in:

  • Event handlers use a try/catch in event handlers.
  • Server-side Rendering
  • Error Boundary Component having Error.

The componentDidCatch() method operates similarly to a catch block in JavaScript, but for components. You'll most likely want to declare an error boundary component once and utilize it across your project. Error boundaries can only be class components.

An error boundary can't catch errors that occur within it. Error boundaries only notice errors in the components in the tree below them. If an error boundary fails to show an error message, the error will spread to the error boundary immediately above it. This, too, is analogous to how JavaScript's catch block works.

Reason To Use

If a JavaScript error occurs within a component, it might cause React's internal state to be corrupted, resulting in cryptic errors. Error boundaries assist in removing these mistakes and the display of a Fallback UI in their place (Which means a display of an error that something broke in the code).

Working Principle

In JavaScript, Error Boundary is quite similar to catch. If an error occurs, it attempts to locate the nearest Error Boundaries Tag as soon as a broken JavaScript component in Rendering or Lifecycle Methods is discovered.

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New Behavior for Uncaught Errors

In React 16, any errors that were not caught by any Error Boundary will result in unmounting the whole React Component Tree.

Leaving the malfunctioning UI exposed in software like Messenger, for example, may result in someone sending a message to the wrong person. Similarly, a payments app displaying an incorrect amount is worse than rendering nothing.

Because of this change, migrating to React 16 will certainly reveal previously undiscovered crashes in your application. When anything goes wrong, adding error boundaries improves the user experience.

We also recommend that you use JS error reporting services (or create your own) to learn about and repair unhandled exceptions as they occur in production.

Component Stack Traces

When an error occurs during program execution, the JVM automatically displays a stack trace. During the execution of a program, the stack trace is used to track the active stack frames at any one time.

Even if the application consumes them, React 16 prints all errors during rendering to the console during development. It also offers component stack traces in addition to the error message and the JavaScript stack. Now you can see precisely where the failure occurred in the component tree:

In component stack trace, you can see the line numbers and filenames, and it works by default in Create React App projects:

If you don't want to utilize the Create React App, you can manually add this plugin to your Babel settings. It should be noted that it is just for development purposes and must be disabled in production.

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Why not use Try/Catch?

One question that may cross your mind is why should you learn this new concept when Error Boundaries works like Catch? Try/catch is used with imperative code, while React is declarative by nature, and Error Boundaries help preserve that declarative nature.

Error bounds maintain React's declarative nature and operate as you'd expect. Even if a setState someplace deep in the tree causes an error in a componentDidUpdate method, the issue will correctly propagate to the closest error boundary means that no matter how deep in the tree error has occurred error boundary will still detect the issue but try/catch will not catch all the errors in React.js code.Try/catch will detect errors in an imperative code, whereas React is declarative.

Behavior in React 15 and Earlier

In the past, several Javascript errors were used to corrupt React’s internal state and caused cryptic errors on the next renders. React couldn’t handle these errors gracefully as an earlier error caused these errors in the application code. As a result, React could not recover from them.

Naming Changes from React 15

In React 15, error boundaries had extremely limited support under a distinct method name.
Unstable handle: This function does not work with the first React 16 beta version and must be replaced with componentDidCatch in code.

Error Handling Best Practices

Using Error Boundaries to Handle Errors -For Class Components :

  • The easiest and effective way to handle problems within your React components is to use error boundaries. If you use a class component, you may construct an error boundary component by inserting the life cycle method componentDidCatch(error, info). This function should be used to log error data to your selected error logging service.
  • Try-Catch Error Handling: Catching Errors Beyond Boundaries:
    Because they don't catch exceptions cascaded from child components, try-catch blocks aren't the best solution to manage component-level exceptions.
    On the other hand, try-catch blocks are used to handle mistakes that aren't caught by error boundaries.
  • Using react-error-boundary Library: The react-error-boundary package makes error handling in React easier, and it's the most effective way to get over the constraints of the basic error boundaries. It allows you to show a fallback component, log errors similarly to simple error boundaries, and reset the application's state to prevent recurring issues.
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React developers can use react-error-boundary to reduce the amount of code they have to write and increase the capabilities of their error borders to catch various types of problems that conventional error boundaries wouldn't catch. Remember that anything in your Error Boundary's child component tree is affected if it throws an error. So be cautious when creating one to avoid making mistakes.