All about functions

Let's get started with a short review of functions in JS and their relationship to FP concepts. We can start something we mentioned in previous chapters, about functions as first-class objects, and then go on to several considerations about their usage in JS.

Of lambdas and functions

In lambda calculus terms, a function can look like λx.2*x. The understanding is that the variable after the λ character is the parameter for the function, and the expression after the dot is where you would replace whatever value is passed as an argument.

If you sometimes wonder about the difference between arguments and parameters, a mnemonic with some alliteration may help: Parameters...