How Effective is Cache Busting with Query Parameters?

Cache Busting via Query Parameters

When deploying updates to production environments, it's essential to ensure that clients receive the latest assets without unnecessary delays. One widely adopted approach for achieving this is cache busting.

To implement cache busting, a query parameter is appended to the end of CSS and JS file URLs, with the current version number included. This method hinges on two questions:

1. Will this technique effectively break the cache?

The query string (?v=1.123) indicates a unique path to the browser. Therefore, it perceives the URL as a fresh path, causing it to retrieve the file from the server instead of relying on the cached version.

2. Will the parameter prevent the browser from caching the response?

Despite the presence of the parameter, the browser assumes that the source will remain unchanged when it encounters the same query string in future requests. Consequently, it will cache the asset with that parameter, continuing to retrieve it from cache until a new parameter (e.g., ?v=1.124) is used.

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