Greetings @cryptospa!
First of all, that's awesome! It takes quite the determination to change your profession after so many years.
Regarding learning JavaScript as your first language, go for it! I am mostly a web dev so I absolutely love it!
But be careful about one thing: usually variables have a type. On languages like Java and C++, you have to declare a variable like "int n=0" in order to declare that "n" will be a number.
On JavaScript this does not happen as you declare a variable as var and it's type varies depending on what you put inside of it.
So be careful in the future regarding this aspect.
Thank you very much for your feedback and good luck on your endeavours!