Does JavaScript support partial function application?

Question

Reading through the Wikipedia article on First-Class functions, there is a nice table of language support for various aspects of functional programming: http://en.wikipedia.

Answer 1

What you show is an example of higher order functions, functions that take functions as arguments and/or return functions.

Partial application is something different. Here a Haskell example:

add     :: Int -> Int -> Int
add x y = x + y

addOne = add 1

add is a function that takes two Int and returns an Int, denoted as Int -> Int -> Int. If you're unfamiliar with the syntax, in Javascript this would roughly look like this:

/**
 * @param int x
 * @param int y
 * @return int
 */
function add(x, y) {
    return x + y;
}

add 1 calls this function with only one parameter, which returns a new function that takes one Int and returns an Int (Int -> Int). The add function was not explicitly designed to be a higher order function, it was simply partially applied.