set of ES2015 functions aimed to make functional JavaScript more idiomatic

gist link

mandatory parameters via parameter default values

  function mandatory() {
        throw new Error('Missing parameter');
    }
    function foo(mustBeProvided = mandatory()) {
        return mustBeProvided;
    }

From: http://www.2ality.com/2016/05/six-nifty-es6-tricks.html