|> is (not, see below) mere function composition function compose(f, g) { return function inner(x) { return f(g(x)); } } this is n

|> is (not, see below) mere function composition function compose(f, g) { return function inner(x) { return f(g(x)); } } this is not the right kind of composition for something like nested callbacks. For that you need slightly more. Edit: It's actually the "apply" operator which looks like function apply(f) { return function applied(x) { return f(x); } } Apply and compose work together nicely. For instance, in Haskell apply is ($) and compose is (.), so you can build a compositional pipeline and apply it like f . g . h $ x or like f $ g $ h $ x since association goes this way f $ (g $ (h $ x))