What is the "blob:http://" prefix and where can I learn more about this?

Solution 1:

Blob URI/URL was created by JavaScript, refers to data that your browser currently has in memory (only in current page), and does not refer to data the exists on the host.

For more information to use, see: https://www.npmjs.com/package/blob-util

Solution 2:

The start of a URL up to the first colon is called a "URI scheme" (or "URL scheme"). Googling for blob URI scheme reveals the W3C's File API efforts.

Most URI schemes don't have standard provisions for containing a whole other URI, so you wouldn't think of them as prefixing another whole URI. Besides http: and https:, some common URI schemes include:

• ftp:
• mailto:
• data:
• script:
• smb: (and cifs: )
• afp:

…and many more. I'm sure I'm leaving out everyone's favorites. :)

Solution 3:

I copy and paste the answer from StackOverflow because of background info about blob in URL string.

A URL that was created from a JavaScript Blob can not be converted to a "normal" URL.

A blob: URL does not refer to data the exists on the server, it refers to data that your browser currently has in memory, for the current page. It will not be available on other pages, it will not be available in other browsers, and it will not be available from other computers.

Therefore it does not make sense, in general, to convert a Blob URL to a "normal" URL. If you wanted an ordinary URL, you would have to send the data from the browser to a server and have the server make it available like an ordinary file.

It is possible convert a blob: URL into a data: URL, at least in Chrome. You can use an AJAX request to "fetch" the data from the blob: URL (even though it's really just pulling it out of your browser's memory, not making an HTTP request).

Solution 4:

MDN is a good resource for understanding things in plain language. I would also suggest https://developer.mozilla.org/en-US/docs/Web/API/URL/createObjectURL as a good resource. They also show the W3C specification at the bottom of their page, the same one as Spiff provided, but the original specifications can be verbose and difficult to read. I would say Spiff is the most correct for linking you to the W3C docs.

I don't think that the link to npmjs that Masoud provided is very useful. It directs you to a Javascript library on the library host npmjs. The blob-util library is used to wrap around the standard API in the browser to work with blobs and it simplified writing code for these things, but it is not a good reference to understand the blob URLs and what they are.