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
What is Lightning Locker?
JavaScript Strict Mode Enforcement
DOM Access Containment
Secure Wrappers
eval() Function is Limited by Lightning Locker
MIME Types Permitted
Access to Supported JavaScript API Framework Methods Only
What Does Lightning Locker Affect?
Lightning Locker Tools
Lightning Locker API Viewer
Locker Console Overview
Evaluate JavaScript Code Compatibility with Lightning Locker
Benchmark Lightning Locker Effect on JavaScript Code
Select the Locker API Version for an Org
Disable Lightning Locker for a Component
Don’t Mix Component API Versions
Lightning Locker Disabled for Unsupported Browsers
Content Security Policy Overview
Using JavaScript
Working with Salesforce Data
Testing Components with Lightning Testing Service
Debugging
Performance
Reference
PDF

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Evaluate JavaScript Code Compatibility with Lightning Locker

Ensure that your code is compatible with Lightning Locker by running the code with Locker enabled. Run the code a second time with Locker disabled to see if any errors are due to Lightning Locker restrictions.

Let's look at an example that uses a prohibited DOM API.

  1. Paste this code into the console.
    1var controller = new AbortController();
2controller;
  2. Click Evaluate.

    Note the error in the LOCKER ON column of the results window.

    1Error: AbortController is not a constructor

    You get this error because AbortController is an experimental interface in the DOM API and is not allowed by Lightning Locker.

    The LOCKER OFF column shows N/A as this column isn't relevant when the Locker toggle is enabled.

  3. Click the Locker toggle to disable Lightning Locker.
  4. Click Evaluate to rerun the code sample with Lightning Locker disabled.

    The second row of the results window shows there's no longer an error when Lightning Locker is disabled. The LOCKER OFF column shows [object AbortController], which is the return value of the sample code.

    Locker Console evaluate results

Use the Locker API Viewer to see the DOM APIs exposed by Lightning Locker versus the standard DOM APIs for the most complex wrappers: SecureDocument, SecureElement, and SecureWindow.