Using methods as (curried) functions in JavaScript [closed]

Question

What is the most elegant way to convert a method to a curried function, and is there support for this in libs like Underscore/Lo-dash or Ramda?

For a fixed number of arguments I'm doing this right now:

var fn2 = _.curry(function (m, a1, a2, obj) {
  return obj[m].call(obj, a1, a2);
});

which allows for code like:

var a2b = fn2('replace', 'a', 'b')
a2b('abc')
=> 'bbc'

as well as:

var nl2_ = fn2('replace', '<br>')
nl2_('\n', 'some<br>html')
=> 'some\nhtml'

Answer 1

You can easily extend your approach for methods with arbitrary arity:

function curryMethod(m, a) {
    if (a !== ~~a) a = m.length;
    return _.curry(function() {
        return m.apply(arguments[a], Array.prototype.slice.call(arguments, 0, -1));
    }, a+1);
}

> var replace = curryMethod(String.prototype.replace)
> replace("a", "b", "abc")
"bbc"
> var a2b = replace("a", "b")
> a2b("abc")
"bbc"

---

Since you also have asked about Ramda, I've only quickly scanned their API but found the R.invoker function which seems to be exactly what you're looking for.