JS built-in pseudo parameter (arguments)

gistfile1.txt

// All JS functions receive 2 pseudo parameters - arguments and this.
// The following uses JS built-in pseudo parameter (arguments).
// arguments is an array-like thing that contains all the arguments passed to the function
// if an argument changes, arguments also changes which can sometimes slow things down
// can access arguments.length
// and can use arguments to manipulate values passed to the function

function sum() {
  'use strict';
  var i = 0, total = 0;
  for (; i < arguments.length; i++) {
    total += arguments[i];
  }
  return total;
}

sum(1,1,1,1);  // 4
var mySum = sum(1,2,3,4,5);  // 15
console.log(sum(2, 4));  // 6