Resenje zadatka

Dev ops

var n,i;
for(n=100,i=0;i<n;){
	console.log( ((++i%3? '' : 'Dev') + (i%5? '' : 'Ops')) || i );
}

Factorial

function f(n) {
	if(n==0) return 1;
	return n*f(n-1);
}

console.log(f(5));

Is prime

function isPrime(num) {
  for(var i = 2; i < num; i++) {
  	if(num % i === 0) return false;
  } 
  return num !== 1;
}

console.log(isPrime(73) ? 'Prime' : 'Composite');

Merging arrays

var foo = [1, 2, 3, 5, 7];
var bar = [1, 4, 6, 7, 8,7];

function mergeArrays(arr1,arr2) {
	var output = arr1.concat(arr2.filter(function (item) {
	    return arr1.indexOf(item) == -1;
	}));
	return output.sort(function(a, b){return a-b});
}

console.log(mergeArrays(foo,bar));