Function isDigit

http/unstable_structured_fields.ts:455–458

Check if character is a digit (0-9)

(c: string)

/** Check if character is a digit (0-9) */
function isDigit(c: string): boolean {
  const code = c.charCodeAt(0);
  return code >= CHAR_CODE_0 && code <= CHAR_CODE_9;
}

/** Check if character is lowercase alphabetic (a-z) */
function isLcalpha(c: string): boolean {