Sometimes, when you visit a website, you may see the following message, pop up in your web browser:
This website is asking for permission to store data on your computer for offline use
You will be offered 3 options – Allow, Never for this site or Not now.
The reason you see this message is because the website you are visiting is asking for permission to use the HTML5 Offline Web Applications API. This is used to store offline web applications and their resources, so that you can access the app, even when you are offline, unlike other common web applications, which require you to stay online.
The HTML 5 specification provides two solutions to this. Firstly, an SQL-based database API for storing data locally in the HTML5 Offline Web Application Store Cache, and secondly an offline application HTTP cache for ensuring applications are available even when the user is not connected to their network.
Many websites, including Bing.com, ask to do this, when they want to store offline HTML5 web applications, in this cache, which is different from the regular browser cache.
In Firefox, you get to access this setting in Options > Network tab > Offline web content and user data.
Although it is not recommended that you do this, Firefox does allow you to turn off this message, you can uncheck Tell me when a website asks to store data for offline use.
You can add exceptions here, clear stored cache and remove sites. Click on the image to see its larger version.
Turning off the message can expose your computer to risks, since you would not know when websites or web app developers may push files on to your Windows computer. So it is best to leave this ‘on’, and allow only content from sites you trust completely.
Thanks for the image and post idea Corrine.