Why Modern CMS Platforms Still Bundle jQuery

Despite the rise of modern JavaScript frameworks and the maturation of native browser APIs, platforms like WordPress still bundle jQuery by default. While developers today can accomplish most tasks with standard vanilla JavaScript, content management systems must balance modern development standards with the needs of a massive, long-standing user base. This article examines the core reasons behind this ongoing reliance, focusing on backward compatibility, third-party ecosystem dependencies, administrative legacy architecture, and the strategic challenges of phasing out deeply embedded software.

Backward Compatibility and Site Stability

The primary reason modern CMS platforms continue to ship jQuery is backward compatibility. WordPress powers over 40% of the web, running on millions of websites with varying code ages. Removing jQuery from the core software would instantly break millions of active sites. CMS maintainers prioritize stability and zero-breakage updates, ensuring that an automated minor or major update does not take a business offline due to missing JavaScript dependencies.

Massive Plugin and Theme Ecosystems

CMS platforms owe much of their popularity to extensive third-party ecosystems. WordPress, for example, hosts tens of thousands of free and premium plugins and themes. A substantial portion of these extensions—ranging from simple sliders and form validators to complex e-commerce add-ons—were built using jQuery. If a CMS stopped bundling the library, theme and plugin authors would either need to rewrite years of code or bundle their own redundant versions of jQuery, which would create conflicts and degrade site performance.

Core Administrative Dependencies

Much of the underlying code inside the administrative dashboards of older CMSs was authored when jQuery was the industry standard for DOM manipulation and AJAX requests. In WordPress, features such as media uploads, drag-and-drop menu management, and meta boxes historically relied on jQuery and jQuery UI. While modern features like the Block Editor (Gutenberg) are built using React and native JavaScript, the legacy administrative interface still requires jQuery to function properly.

Developer Familiarity and Low Barrier to Entry

jQuery remains one of the most accessible JavaScript libraries ever created. Its simple syntax allows non-specialist developers, site builders, and designers to add interactivity without mastering complex build steps, compilers, or advanced JavaScript concepts. By keeping jQuery readily available, CMS platforms maintain a low barrier to entry for creators who want to implement functional scripts quickly.

The Shift Toward Gradual Decoupling

Modern CMSs are not ignoring modern web standards; they are simply decoupling gradually rather than abruptly. For instance, modern WordPress front-end features increasingly avoid jQuery dependencies, and core developers actively work to remove jQuery from user-facing templates. However, until the vast ecosystem fully transitions to native APIs or headless architectures, bundling jQuery remains the safest and most practical choice for web-scale platforms.