sample_3.js

function findCheapest(orders) {
	var cheapest = 999999999;
	for (i=0; i<orders.length; i++) {
		cheapest = Math.min(cheapest, findCheapestItem(orders[i].items) );
	}
	return cheapest;
}

function findCheapestItem(items) {
	var cheapest = 999999999;
	for (i=0; i<items.length; i++) {
		cheapest = Math.min(cheapest,items[i].cost);
	}
	return cheapest;
}

var orders = [{id:1, items: [{cost:100.00},{cost: 95.00}]},
              {id:2, items: [{cost:90.00},{cost: 120.00}]}
             ];
alert( findCheapest(orders) );