Function countCharInString

src/utils/stringUtils.ts:54–66

(
  str: { indexOf(search: string, start?: number): number },
  char: string,
  start = 0,
)

 * (Buffer.indexOf accepts string needles).
 */
export function countCharInString(
  str: { indexOf(search: string, start?: number): number },
  char: string,
  start = 0,
): number {
  let count = 0
  let i = str.indexOf(char, start)
  while (i !== -1) {
    count++
    i = str.indexOf(char, i + 1)
  }
  return count
}

/**
 * Normalize full-width (zenkaku) digits to half-width digits.