Вазген Алексанян

let check = true;
let latestFriendlyAnimal = '';

function sayHello(animal) {

  if(check && !(['lion', 'cat', 'dog', 'cow'].includes(animal))) return "Growl"
  
  if((check && animal === 'lion') || ['dog', 'cat', 'cow'].includes(animal)) {
  	latestFriendlyAnimal = animal
    return animal
  }
  
  return 'Hello';
}

console.log(sayHello('dog'));

console.log(latestFriendlyAnimal);

<meta name="viewport" content="width=device-width, initial-scale=1">

$('.number-input').on('keypress', function(e){
		if(!e.key.match(/^[0-9]+$/)){
			return false;
		}
	});

let arr = ["fold/css/bootstrap.css", "fold/css/magnific-popup.css","fold/css/animate.css","fold/css/style.css"];
for(let i = 0; i < 4; i++){
var link_css = document.createElement( "link" );
link_css.rel = 'stylesheet';
link_css.href = arr[i];
document.head.appendChild(link_css);
}

div1.addEventListener('mousemove', function(){
	div2.style.color = 'red';
});