JS arguments

var array = [1,2,3,4];

array = array.map(function(x) {
  return x*x;
})

console.log("regular array", array); // [1,4,9,16]

function foo() {
	array = arguments.map(function(x) {
		return x*x;
	});
	console.log("arguments", array); 
}

//foo(1,2,3,4); //error: Object #<Object> has no method 'map'

// hence why we might do:

function betterFoo() {
	var args = Array.prototype.slice.call(arguments);
	array = args.map(function(x) {
		return x*x;
	});
	console.log("arguments -> array", array);
}

betterFoo(1,2,3,4); // [1,4,9,16]