There is a fundamental difference between being a contractor and being a permy. If you are contractor and you are being tested for a framework - this is perfectly fine and this is why you consider it as a norm. You work there for three to twelve months and you need to start delivering value from day one.
If we are talking about a permanent position, there is a different story. If a company is serious about their people - they will train you for this framework considering you are good at front-end and JS in general. Pair-programming and some introductory course will set your track, then you can do stuff yourself. If a company is not ready to invest at least this to people they consider to work there for many years - I would seriously doubt their intentions in general. If a company doesn't even understand the point - even worse.
You might be right, I just assume the best as I've had almost no negative experiences during my career, whether as freelancer of working for companies. As an employee, I do value an on-boarding period to get familiar with the stack, but with my experience also feel like I should be able to deliver / contribute quite early on.
Have you had any experiences with companies or even interviews for companies that expected you to be up and running from day one?
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