revision:
The charCodeAt() method returns the Unicode of the character at a specified index (position) in a string.The index of the first character is 0, the second is 1, .... The index of the last character is string length - 1.
string.charCodeAt(index)
Parameters:
index : optional. A number. The index (position) of the character to be returned. Default is 0.
<p>charCodeAt() returns the Unicode of the character at a specified position in a string.</p>
<p>Get the Unicode of the first character:</p>
<p id="demo"></p>
<script>
let text = "HELLO WORLD";
let letter = text.charCodeAt(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.charCodeAt(1);
document.getElementById("at-2").innerHTML = "code : " + code;
let code2 = text.charCodeAt(text.length-1);
document.getElementById("at-3").innerHTML = "code : " + code2;
let code3 = text.charCodeAt(15);
document.getElementById("at-4").innerHTML = "code : " + code3;
let code4 = text.charCodeAt();
document.getElementById("at-5").innerHTML = "code : " + code4;
</script>