bkp7 / mdprepare

export function replaceLineEndings (txt, CRLF) {

  // replaces line endings within txt, with CRLF if CRLF is true, otherwise just LF

  if (CRLF === true) {

    // NB can't do the replacement of '\n' with '\r\n' using regex due to javascript limitations

    let p = 0 // current position in the string

    let x = 0 // location of '\n' in the string

    let t = '' // output string

    while (true) {

      x = txt.indexOf('\n', p)

      if (x === -1) {

        // we've not got any more '\n' in the string so complete and exit

        t = t + txt.substr(p)

        return t

      } else if (x === 0 || txt.substr(x - 1, 1) !== '\r') {

        t = t + txt.substring(p, x) + '\r\n'

        p = x + 1

      } else {

        t = t + txt.substring(p, x + 1)

        p = x + 1

      }

    }

  } else {

    return txt.replace(/(\r\n)/g, '\n')

  }

}