Regular expression to accept only characters (a-z) in a textbox

Question

What is a regular expression that accepts only characters ranging from a to z?

Answer 1

None of the answers exclude special characters... Here is regex to ONLY allow letters, lowercase and uppercase.

/^[_A-zA-Z]*((-|\s)*[_A-zA-Z])*$/g

And as for different languages, you can use this function to convert letters to english letters before the check, just replace returnString.replace() with letters you need.

export function convertString(phrase: string) {
    var maxLength = 100;

    var returnString = phrase.toLowerCase();
    //Convert Characters
    returnString = returnString.replace("ą", "a");
    returnString = returnString.replace("č", "c");
    returnString = returnString.replace("ę", "e");
    returnString = returnString.replace("ė", "e");
    returnString = returnString.replace("į", "i");
    returnString = returnString.replace("š", "s");
    returnString = returnString.replace("ų", "u");
    returnString = returnString.replace("ū", "u");
    returnString = returnString.replace("ž", "z");

    // if there are other invalid chars, convert them into blank spaces
    returnString = returnString.replace(/[^a-z0-9\s-]/g, "");
    // convert multiple spaces and hyphens into one space
    returnString = returnString.replace(/[\s-]+/g, " ");
    // trims current string
    returnString = returnString.replace(/^\s+|\s+$/g, "");
    // cuts string (if too long)
    if (returnString.length > maxLength) returnString = returnString.substring(0, maxLength);
    // add hyphens
    returnString = returnString.replace(/\s/g, "-");

    return returnString;
}

Usage:

const firstName = convertString(values.firstName);

            if (!firstName.match(allowLettersOnly)) {
            }