JavaScript & regex : How do I check if the string is ASCII only?

May 9, 2023 by Tarik

All you need to do it test that the characters are in the right character range.

function isASCII(str) {
    return /^[\x00-\x7F]*$/.test(str);
}

Or if you want to possibly use the extended ASCII character set:

function isASCII(str, extended) {
    return (extended ? /^[\x00-\xFF]*$/ : /^[\x00-\x7F]*$/).test(str);
}