Whenever you’re debugging caching issues, one valuable source of information are the HTTP Cache Headers that are present in the requests. There are multiple ways to see what headers are sent with your requests. We’ll show you two methods of obtaining them.
Method 1: using your browser
Most modern browser come with some kind of developer tools. You can use these to get a plethora of information about the website you’re visiting. One of the things you can check is the headers sent and received with your requests. For people that aren’t comfortable using command line tools this is the preferred method.
This is how you see them in Chrome:
First we open up the inspector. You can do so by right clicking anywhere on the page you want to inspect and choose the last option:
Now, we navigate to the Network tab. Make sure the checkbox at Disable Cache is checked, and reload the page. Find the first request made to your page (usually the top one) and click it. You will get more details on this specific request. The information we need is in the Headers tab:
This is how you see them in FireFox:
First we need to open up the Inspector. The quickest way to get there would be by right clicking anywhere on the page you want to inspect and choose the appropriate option:
When it’s open, we go to the Network tab, make sure the checkbox for Disable Cache is ticked, and reload the page. You will be presented with a (usually) large list of all HTTP requests made by the browser to render your page. Scroll all the way to the first request made (depends on sorting, but usually on top of the list) and click it. This will give you the needed information:
Method 2: using the command line interface
Most modern operating systems come shipped with a versatile command line tool known as Curl. There are of course different ways to get the information we need, but for simplicity we’ll stick to this tool for now. With Curl you can use the -I option to fetch only the headers of the resource you requested:
As you can see, this provides you with a lot more headers than just the caching headers we’re looking for. This is what makes Curl such a powerful tool at debugging various things, and not just looking at caching headers.
That’s it! Now you know how you can retrieve those HTTP cache headers whenever you need them.
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