code: function parseLength (parser) {
    const length = parser.buffer.length - 1
    var offset = parser.offset
    var number = 0
  
    while (offset < length) {
      const c1 = parser.buffer[offset++]
      if (c1 === 13) {
        parser.offset = offset + 1
        return number
      }
      number = (number * 10) + (c1 - 48)
    }
  }
docs: Returns the read length
  @param {JavascriptRedisParser} parser
  @returns {undefined|number}