Kata

Write a function defaultArguments. It takes a function as an argument, along with an object containing default values for that function's arguments, and returns another function which defaults to the right values.

You cannot assume that the function's arguments have any particular names.

You should be able to call defaultArguments repeatedly to change the defaults.

function add(a,b) { return a+b;};

var add_ = defaultArguments(add,{b:9});
add_(10); // returns 19
add_(10,7); // returns 17
add_(); // returns NaN

add_ = defaultArguments(add_,{b:3, a:2});
add_(10); // returns 13 now
add_(); // returns 5

add_ = defaultArguments(add_,{c:3}); // doesn't do anything, since c isn't an argument
add_(10); // returns NaN
add_(10,10); // returns 20

add = (a, b) -> a + b

add_ = defaultArguments(add, {b: 9})
add_ 10 # returns 19
add_ 10, 7 # returns 17
add_() # returns NaN

add_ = defaultArguments(add_, {b: 3, a: 2})
add_ 10 # returns 13 now
add_() # returns 5

add_ = defaultArguments(add_, {c:3}) # doesn't do anything, since c isn't an argument of add_
add_ 10 # returns NaN
add_ 10, 10 # returns 20

HINT: This problem requires using Fuction.prototype.toString() in order to extract a function's argument list