How to count unaccented English letters in Javascript?

I'm trying to count the number of characters that are unaccented English letters in a string. For example, I would want the count to be 1 for the string "né!".

I thought I would be able to check if each character is in the range 'a'-'z' or 'A'-'Z', but that would include 'é':

'é' >= 'a' && 'e' <= 'z';
true

Both accented and unaccented letters seem to have the same code point:

"eé".codePointAt(0);
101
"eé".codePointAt(1);
101

I tried using regular expressions, but the string "né!" was treated like the 4-character string "ne'!":

	for (let i = 0; i < len; i++) {
	    var c = str.charAt(i);
	    if (re.test(c)) {
		    console.log("Is a letter: " + c);
		    numLetters++;
	    } else {
		   console.log("Is not a letter: " + c);
	    }
	}

Output:

Is a letter: n
Is a letter: e
Is not a letter: ́
Is not a letter: !

How can I find the number of characters that are unaccented English letters?

You can use String#normalize to get the composed form of a string.

<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-js -->

let str = "né!";
let letters = str.normalize().match(/[a-z]/ig);
console.log(letters?.length ?? 0);
console.log(letters);

<!-- end snippet -->