Function isAlpha

http/unstable_structured_fields.ts:448–452

Check if character is alphabetic (A-Z or a-z)

(c: string)

/** Check if character is alphabetic (A-Z or a-z) */
function isAlpha(c: string): boolean {
  const code = c.charCodeAt(0);
  return (code >= CHAR_CODE_UPPER_A && code <= CHAR_CODE_UPPER_Z) ||
    (code >= CHAR_CODE_LOWER_A && code <= CHAR_CODE_LOWER_Z);
}

/** Check if character is a digit (0-9) */
function isDigit(c: string): boolean {