Cache busting strategies in Flask - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is cache busting in web development?

Cache busting is a technique used to force browsers to load the latest version of files like CSS or JavaScript by changing their URLs, so old cached versions are not used.

beginner

How does adding a query string like ?v=123 help with cache busting?

Adding a query string changes the file URL, making the browser treat it as a new resource and fetch the updated file instead of using the cached one.

intermediate

What is the role of Flask's url_for() function in cache busting?

Flask's url_for() can add a version or timestamp as a query parameter to static file URLs, helping to automatically update URLs when files change.

intermediate

Explain the difference between 'query string versioning' and 'file name versioning' for cache busting.

'Query string versioning' adds a version number as a parameter (e.g., style.css?v=2), while 'file name versioning' changes the file name itself (e.g., style.v2.css). Both force browsers to load new files.

beginner

Why is cache busting important when deploying updates in Flask applications?

Without cache busting, users might see old styles or scripts because browsers use cached files. Cache busting ensures users get the latest updates immediately after deployment.

Which method can Flask use to help with cache busting of static files?

A Renaming the Flask app file

B Disabling the browser cache completely

C Using <code>url_for()</code> with a version query parameter

D Changing the Python version

Flask's url_for() can add version info to static file URLs to force cache refresh.

What happens if you do NOT use cache busting after updating CSS files?

A Browsers may load old cached CSS, showing outdated styles

B The server crashes

C The CSS file size increases

D The browser disables JavaScript

Without cache busting, browsers often use cached files, so updates may not appear.

Which is a common cache busting strategy in Flask apps?

A Changing the Flask secret key

B Adding timestamps or version numbers to static file URLs

C Using inline CSS only

D Disabling Flask debug mode

Adding timestamps or versions to URLs forces browsers to fetch new files.

What is a downside of using query strings for cache busting?

A It increases server CPU usage drastically

B It breaks the Flask app

C It disables browser caching completely

D Some CDNs may ignore query strings and cache old files

Some CDNs do not cache files with query strings properly, so file name versioning can be better.

How can you automate cache busting in Flask?

A By adding a hash or timestamp to static file URLs using <code>url_for()</code>

B By manually renaming files every time

C By disabling static file serving

D By using Flask's <code>render_template()</code> only

Automating versioning with url_for() helps keep URLs updated without manual changes.

Describe what cache busting is and why it matters in Flask web apps.

Think about how browsers store files and how changing URLs can force updates.

List and explain two common cache busting strategies used in Flask applications.

Consider how URLs change and how CDNs might react.