Дмитрий

let slovo = document.querySelector('#word').textContent;

.test2{
    background-color: black;
    color: #fff;
}
.test:hover + .test2{
    background-color: blue;
}

let items = document.querySelectorAll('p');

for(let i = 0; i < items.length; i++){
		items[i].addEventListener('click', function(){
    	alert(i);
    });
}

function sumArr(arr, index){		
		var sum = 0;		
		for(var i = index; i < arr.length; i++){
			sum += arr[i];
		}
		return sum;		
	}
	console.log(sumArr([1,2,3,4,5,6], 3));

<button onclick="return confirm('Post will been deleted! Are you sure ?')">Delete</button>