This is a quote from the O’Reilly Javascript Patterns book:
JavaScript is also an unusual language. It doesn’t have classes, and
functions are first class objects used for many tasks. Initially the
language was considered deficient by many developers, but in more
recent years these sentiments have changed. Interestingly, languages
such as Java and PHP started adding features such as closures and
anonymous functions, which JavaScript developers have been enjoying
and taking for granted for a while.
and that’s it. I really don’t understand how Javascript was considered “deficient” before, and now is not, because other languages like Java or PHP has added closures and anonymous functions? Aren’t they just generic computing concepts? Aren’t they available in other languages like Ruby? So I don’t really know how Javascript is now not “deficient” because Java and PHP added closures and anonymous functions as their features? Why is that?
I think what it’s referring to is that in the past many developers considered JavaScript as a ‘toy’ language and only used it to do quick Web UI tasks like validation etc. without bothering to understand how the language really worked.
In recent years the ‘hidden’ features of JavaScript such as closures, prototypal inheritance etc. have come to the fore and people are now taking JavaScript much more seriously as a ‘real’ language.
So JavaScript was never really “deficient” but people may have thought that it was due to their misconceptions about the language.