constructor(usingCheckDigit = false, extendedMode = false) {
			super();
			this.usingCheckDigit = usingCheckDigit;
			this.extendedMode = extendedMode;
			this.decodeRowResult = '';
			this.counters = new Int32Array(9);
		}
Creates a reader that can be configured to check the last character as a check digit,
or optionally attempt to decode "extended Code 39" sequences that are used to encode
the full ASCII character set.

@param usingCheckDigit if true, treat the last data character as a check digit, not
data, and verify that the checksum passes.
@param extendedMode if true, will attempt to decode extended Code 39 sequences in the
text.