Lightning Aura Components Developer Guide

What Is the Lightning Component Framework?
Quick Start
Creating Components
Using Components
Communicating with Events
Communicating Across the DOM with Lightning Message Service
Creating Apps
Styling Apps
Developing Secure Code
Using JavaScript
Supported JavaScript
Invoking Actions on Component Initialization
Sharing JavaScript Code in a Component Bundle
Sharing JavaScript Code Across Components
Using External JavaScript Libraries
Dynamically Creating Components
Detecting Data Changes with Change Handlers
Finding Components by ID
Working with Attribute Values in JavaScript
Working with a Component Body in JavaScript
Working with Events in JavaScript
Modifying the DOM
Checking Component Validity
Modifying Components Outside the Framework Lifecycle
Throwing and Handling Errors
Calling Component Methods
Dynamically Adding Event Handlers To a Component
Dynamically Showing or Hiding Markup
Adding and Removing Styles
Which Button Was Pressed?
Formatting Dates in JavaScript
Using JavaScript Promises
Making API Calls from Components
Manage CSP Trusted Sites
Working with Salesforce Data
Testing Components with Lightning Testing Service
Debugging
Performance
Reference
PDF

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Throwing and Handling Errors

The framework gives you flexibility in handling unrecoverable and recoverable app errors in JavaScript code. For example, you can throw these errors in a callback when handling an error in a server-side response.

Unrecoverable Errors

Don’t depend on the internals of a Lightning base component for error handling as its internals can change in future releases. Errors that are recoverable can change into unrecoverable errors and vice versa. If you encounter an unexpected error, you can sometimes get more information by enabling debug mode.

Note

Use throw new Error("error message here") for unrecoverable errors, such as an error that prevents your app from starting successfully. The error message is displayed.

$A.error() is deprecated. Throw the native JavaScript Error object instead by using throw new Error().

Note

This example shows you the basics of throwing an unrecoverable error in a JavaScript controller.

Here is the client-side controller source.

Recoverable Errors

To handle recoverable errors, use a component, such as ui:message, to tell users about the problem.

This sample shows you the basics of throwing and catching a recoverable error in a JavaScript controller.

Here is the client-side controller source.

The controller code always throws an error and catches it in this example. The message in the error is displayed to the user in a dynamically created ui:message component. The body of the ui:message is a ui:outputText component containing the error text.