Edit in JSFiddle

//iterate character by character
// modern js

for (let char of "Hello") {
 document.getElementById("result").innerHTML += char+"<br />"; // H,e,l,l,o (char becomes "H", then "e", then "l" until last character)
}

<h1>String</h1>

<h2>iterate character by character</h2>

<blockquote>
result:<br />
<span id="result"></span>
</blockquote>