ES5 vs ES6 function for fix a function to take up to N-arguments (see N-ary or arity)

ary.js

// pre-ES6
function _ary(fn, arity) {
    arity = arity || 1;
    return function() {
        // could use Array.from(arguments).slice(0, arity) ?
        var args = Array.prototype.slice.call(arguments, 0, arity);
        return fn.apply(null, args);
    };
}

// ES6 version... lovely!
const _ary = (fn, arity = 1) => (...args) => fn(...args.slice(0, arity));

// try it:

var log1 = _ary(console.log);
var log3 = _ary(console.log, 3);

log1("will", "only", "take", "the first");
// output: will

log3("will", "only", "take 3 arguments", "and ignore all", "the others");
// output: will only take 3 arguments