Javascript has a terrible embarrassment of a standard library. Things that should just be baked into the language are not, which has lead to attempts to rectify that shortcoming, like jQuery, Underscore and LoDash. Because this standard library isn't implemented in the browser itself, where it belongs, people have gotten upset about downloading a few hundred kbs of a general purpose utility library, and instead reimplemented different bits of it in a thousand and one ways, nearly all of them more or less subtly broken. (I don't understand the obsession with JS library size - it's completely irrelevant in 95% of cases, compared to the megabytes of other garbage most sites will pull in for trackers and images).