revision:
The charAt() method returns the character at a specified index (position) in a string. The index of the first character is 0, the second 1, ...
string.charAt(index)
Parameters:
index : optional. The index (position) of the character to be returned. Default is 0.
<p>charAt() returns the character at a specified index (position) in a string.</p>
<p>Get the first character in a string:</p>
<p id="demo"></p>
<script>
let text = "HELLO WORLD";
let letter = text.charAt(0);
document.getElementById("demo").innerHTML = letter;
</script>
<p>charAt() returns the character at a specified index (position) in a string.</p>
<p>Get the last character in a string:</p>
<p id="demo"></p>
<script>
let text = "HELLO WORLD";
let letter = text.charAt(text.length-1);
document.getElementById("demo").innerHTML = letter;
</script>
example: using the charAt() method on strings
<div>
<p id="at-1"></p>
<p id="at-2"></p>
<p id="at-3"></p>
<p id="at-4"></p>
<p id="at-5"></p>
<p id="at-6"></p>
<p id="at-7"></p>
</div>
<script>
let text = "HELLO WORLD";
document.getElementById("at-1").innerHTML = "string : " + text;
let letter = text.charAt(1);
document.getElementById("at-2").innerHTML = "second letter : " + letter;
let letter1 = text[1];
document.getElementById("at-3").innerHTML = "second letter : " + letter1;
let letter2 = text.charAt(text.length-1);
document.getElementById("at-4").innerHTML = "last letter : " + letter2;
let letter3 = text.charAt(15);
document.getElementById("at-5").innerHTML = "index out of range : " + letter3;
let letter4 = text.charAt();
document.getElementById("at-6").innerHTML = "letter : " + letter4;
let letter5 = text.charAt(3.14);
document.getElementById("at-7").innerHTML = "invalid index : " + letter5;
</script>