If you have 10 years experience in php and apply a JavaScript role with 3 month non commercial experience. You are a junior dev or intern. At least from employee's view

I completly disagree, if you understand programming paradigms it's easier/faster for you to pick up a new language than for an intern/junior.
And the employer knows that as well. He maybe trys to pay you like a junior, bad that's a stupid move for him,in the longterm.

If you came from a php background and start to do nodejs, front end, ect. You will know what I mean. The way you learn is not much diff compared from Junior. Not saying you don't have advantage. At that particular monent, you will find yourself back to the junior. Went through tutorial, asking ppl, doing all the Junior stuff. Employer will see you don't have much js experience and won't hire you. Think about you are Nokia.

@kenpeter i would hire anybody who has a strong programming background and is motivated to do js.