infinite curried function for sum

inf-curried-sum.js

function f (input, sum = 0) {
  if(!input) { 
    return sum; 
  }
  else {
    return function(nextInput) {
      sum += input; 
      return f(nextInput, sum);
    }
  }
}

// example 
/*
f();               // 0
f(1)();            // 1
f(1)(2)(3)();      // 6
f(3)(2)(5)(6)();   // 16
*/