Ultimately this is a frustrating browser cache issue, which can be solved by forcing the browser to do a “hard refresh”, which is going to be a browser/OS dependent keystroke, but generally this works:
- Windows: Ctrl+F5
- Mac: Cmd+Shift+R
- Linux: Ctrl+Shift+R
There are other filename tricks one can use to avoid this issue (mentioned in comments of the OP). These are especially important in production where you have no control over browser behavior.
For non-Static Flask responses you can set the cache_control.max_age property, which should tell the browser when to expire the response if it is cached. For instance if you have a Flask XHR endpoint that returns JSON data you could do this:
@app.route('/_get_ajax_data/')
def get_ajax_data():
data = {"hello": "world"}
response = jsonify(data)
response.cache_control.max_age = 60 * 60 * 24 # 1 day (in seconds)
return response
You typically can also set default values in your production web server configuration for specific resource types (e.g. CSS/JS/HTML/JSON/etc)
Edit 4/1/2019 (unrelated to April Fools day)
- Mac / Safari keystroke now appears to be: Cmd+Opt+R (via comments, thanks!).
- See the new answer from @MarredCheese for a very elegant “filename trick” to force the browser to ignore cached copies for updated files.