What Is the jQuery $.active Property?

The jQuery.active property (commonly accessed via $.active) is an internal counter used by jQuery to track the number of currently active, pending AJAX requests. This article explains how $.active operates under the hood, its primary use case in end-to-end automated testing, and its key limitations in modern web development.

How $.active Works

Every time an asynchronous request is initiated using a jQuery AJAX method—such as $.ajax(), $.get(), or $.post()—jQuery automatically increments the $.active integer by 1. Once the server responds and the request lifecycle completes (regardless of whether the outcome is a success or an error), jQuery decrements the counter by 1.

When there are no ongoing jQuery AJAX requests, the value of $.active evaluates to 0.

The Primary Role: Test Automation

The $.active property is rarely used in production business logic. Instead, its most prominent role is in automated browser testing using tools like Selenium WebDriver, Cypress, or Puppeteer.

Because modern web applications frequently update the user interface asynchronously, test scripts often encounter race conditions where an element cannot be found because the network call has not yet finished. Automated test suites use $.active to create conditional wait strategies, ensuring that the script only advances once all network traffic has cleared.

In a test script, this is commonly implemented via JavaScript execution:

// Selenium/WebDriver example logic
Boolean isAjaxComplete = (Boolean) jsExecutor.executeScript("return jQuery.active === 0;");

By polling jQuery.active === 0, the testing suite ensures that data fetches and subsequent DOM rendering are finished before running assertions or clicking buttons.

Limitations of $.active

While useful for legacy and jQuery-heavy applications, $.active has notable limitations:

  • Scope Restriction: It only tracks requests managed directly by jQuery. It does not monitor the browser's native fetch() API, raw XMLHttpRequest objects, WebSockets, or third-party HTTP clients like Axios.
  • Non-Standard API: The property is internal to jQuery's implementation and is not officially documented as a stable public API, meaning it could change between major library versions.
  • Modern Framework Incompatibility: In hybrid or component-driven applications (such as React, Vue, or Angular) running alongside jQuery, a value of 0 does not guarantee that the page has finished rendering or updating its internal state.