revision:
The codePointAt() method returns the Unicode of the character at an index (position) in a string.The index of the first character is 0, the second is 1, ....
Difference between charCodeAt() and codePointAt() : charCodeAt() is UTF-16, codePointAt() is Unicode. charCodeAt() returns a number between 0 and 65535. Both methods return an integer representing the UTF-16 code of a character, but only codePointAt() can return the full value of a Unicode value greather 0xFFFF (65535).
string.codePointAt(index)
Parameters:
index : optional. A number. The index (position) of the character in a string. Default is 0.
<p>Get the code point at the first character:</p>
<p id="demo"></p>
<script>
let text = "HELLO WORLD";
let code = text.codePointAt(0);
document.getElementById("demo").innerHTML = code;
</script>
<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 code = text.codePointAt(1);
document.getElementById("at-2").innerHTML = "code : " + code;
let code2 = text.codePointAt(text.length-1);
document.getElementById("at-3").innerHTML = "code : " + code2;
let code3 = text.codePointAt(15);
document.getElementById("at-4").innerHTML = "code : " + code3;
let code4 = text.codePointAt();
document.getElementById("at-5").innerHTML = "code : " + code4;
</script>