How Does Appending Query Parameters to CSS/JS Files Achieve Cache Busting?

Cache Busting by Appending Query Parameters

To enhance caching strategies during production deployments, implementing cache busting is crucial. One approach involves appending a query parameter to CSS and JS files containing the current version number:

<link rel="stylesheet" href="base_url.com/file.css?v=1.123"/>

This approach effectively breaks the cache upon deployment as the browser treats the parameter as a new path, triggering a fresh load from the server rather than relying on cached content.

However, it's important to consider whether the parameter itself affects the caching behavior. The query parameter ?v=1.123 indicates a query string, which typically signifies a unique resource. Consequently, the browser may assume that the content retrieved with this parameter is dynamic and should not be cached.

Fortunately, this is not the case. The browser recognizes that the source remains the same upon subsequent requests with the same parameter value (e.g., ?v=1.123). Therefore, it proceeds to cache the content based on the parameter as long as the version number remains unchanged. This ensures that the content remains cached until a new version is deployed, identified by an updated parameter value (e.g., ?v=1.124).

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