This is funny and sad to me. We had SQLite in the browser[0]. I only did a little bit of work with it but it seemed actually pretty nice. It was torpedoed because it was SQL-based (and not trendy "key value" and "web scale"). There was the whole excuse that the specification was "whatever SQLite does" and, therefore, not suitable for being a standard. There would be worse things than SQLite upon which to base a stand…
The excuse was that a standard needs to have multiple implementations otherwise we are standardising implementation details and bugs. Hindsight shows that was entirely correct, as SQLite bugs were then found that could be exploited directly via WebSQL, Firefox of course was not vunerable. ( https://hub.packtpub.com/an-sqlite-magellan-rce-vulnerabilit... ) As a sidenote, I worked a lot with the WebSQL API and it was n…
For those who are able to stomach an uncomfortable political history instead of an easy, technical answer, you can take a look at [2]. It's interesting that 7 years later, many the folks who pushed hard to get rid of SQL in favor of NoSQL seem to no longer occupy positions of prominence in the industry.
[1] https://developer.mozilla.org/en-US/docs/Web/API/IndexedDB_A...
[2] https://nolanlawson.com/2014/04/26/web-sql-database-in-memor...