Lightning Aura Components Developer Guide

Introducing Aura Components
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
Working with Salesforce Data
Testing Components
Debugging
Performance
Reference
PDF

Note: This release is in preview. Features described here don’t become generally available until the latest general availability date that Salesforce announces for this release. Before then, and where features are noted as beta, pilot, or developer preview, we can’t guarantee general availability within any particular time frame or at all. Make your purchase decisions only on the basis of generally available products and features.

Using JavaScript

Use JavaScript for client-side code. The $A namespace is the entry point for using the framework in JavaScript code.

For all the methods available in $A, see the JavaScript API.

A component bundle can contain JavaScript code in a client-side controller, helper, or renderer. Client-side controllers are the most commonly used of these JavaScript resources.

Expressions in JavaScript Code

In JavaScript, use string syntax to evaluate an expression. For example, this expression retrieves the label attribute in a component.

1var theLabel = cmp.get("v.label");

Only use the {! } expression syntax in markup in .app or .cmp resources.

Note