javascript recursive sum and max

jsrecursion.js

function sumNonRecursive(arr) {
  var n = 0;
  for (var i = 0; i < arr.length; i++) {
    n = n + arr[i];
  }
  return n;
}
   
var numArray = [5,2,3];

console.log(sumNonRecursive(numArray));

//////////

Array.prototype.head = function(){
  return this[0];
};

Array.prototype.last = function(){
  if (this.length == 0) {
    return this;
  }
  else {
    return this[this.length -1];
  }
};

Array.prototype.tail = function(){
  var t = this.splice(0,1);
  return this;
};

function sum(arr) {
  if (arr.length == 0) {
    return 0;
  }
  else {
    return arr.head() + sum(arr.tail());  // This line is returned last (arr.head + 0)
  }
}

var test = sum([1,2,3,6]);
console.log(test);

///////////

function max(arr) {
	if (arr.length == 1) {
		return	arr[0];
	}
	var f = arr.head();
	var l = arr.last();
	return max(f < l ? arr.slice(1) : arr.slice(0, -1));
}

var numbers = [44,46,41,-2,-200,99,124];

console.log(max(numbers));

Thanks. This helped me understand recursion in JS! :)

good stuff thanks