Integrating the MRZ Scanner into a Dynamic Web TWAIN Application

// Used by the Button on page, to trigger a MRZ read with the current select page
async function readMRZ() {
    if (!checkIfImagesInBuffer()) {
        return;
    }
    if (!cvRouter) {
        console.log("cvRouter is not initialized.");
        return;
    }
    let imgURL = DWTObject.GetImageURL(DWTObject.CurrentImageIndexInBuffer);
    let capturedResults = await cvRouter.capture(imgURL, "ReadPassportAndId");
    const recognizedResults = capturedResults.textLineResultItems;
    const parsedResults = capturedResults.parsedResultItems;
    if (!parsedResults || !parsedResults.length) {
        console.log("No Result");
        return;
    }
    
    let extractedResults = JSON.stringify(extractDocumentFields(parsedResults[0]));
    extractedResults = extractedResults.split(",").join("\n");
    extractedResults = extractedResults.replace(/{"text":|[{"}]/g, "");
    document.getElementById("divNoteMessage").innerHTML = extractedResults; // print the result to the result div
}

/**
 * Extracts and returns document fields from the parsed MRZ result
 *
 * @param {Object} result - The parsed result object containing document fields.
 * @returns {Object} An object with key-value pairs of the extracted fields.
 */
function extractDocumentFields(result) {
    if (!result || result.exception) {
    return {};
    }

    const fieldWithStatus = (fieldName, raw=false) => ({
    text: raw ? result.getFieldRawValue(fieldName) : result.getFieldValue(fieldName),
    });

    const parseDate = (yearField, monthField, dayField) => {
        const year = result.getFieldValue(yearField);
        const currentYear = new Date().getFullYear() % 100;
        const baseYear =
            yearField === "expiryYear" ? (parseInt(year) >= 60 ? "19" : "20") : parseInt(year) > currentYear ? "19" : "20";
    
        return {
            text: `${baseYear}${year}-${result.getFieldValue(monthField)}-${result.getFieldValue(dayField)}`,
        };
    };

    // Add special case for Spanish IDs
    const getDocumentNumber = (codeType) => {
    const documentType = mapDocumentType(codeType);
    const documentNumberField =
    documentType === "passport" && codeType === "MRTD_TD3_PASSPORT"
        ? "passportNumber"
        : result.getFieldRawValue("nationality") === "ESP" ? 
        "optionalData1" : "documentNumber";

    const primaryNumber = fieldWithStatus(documentNumberField);
    const longNumber = fieldWithStatus("longDocumentNumber");

    return primaryNumber?.text ? primaryNumber : longNumber;
    };

    // Document Type and Name
    const codeType = result.codeType;

    return {
        Surname: fieldWithStatus("primaryIdentifier"),
        "Given Name": fieldWithStatus("secondaryIdentifier"),
        Nationality: fieldWithStatus("nationality", true),
        "Document Number": getDocumentNumber(codeType),
        "Document Type": documentTypeLabel(codeType),
        "Issuing State": fieldWithStatus("issuingState", true),
        Sex: fieldWithStatus("sex", true),
        "Date of Birth (YYYY-MM-DD)": parseDate("birthYear", "birthMonth", "birthDay"),
        "Date of Expiry (YYYY-MM-DD)": parseDate("expiryYear", "expiryMonth", "expiryDay"),
        "Document Type": JSON.parse(result.jsonString).CodeType,
    };
}

function mapDocumentType(codeType) {
    switch (codeType) {
    case "MRTD_TD1_ID":
        return "td1";

    case "MRTD_TD2_ID":
    case "MRTD_TD2_VISA":
    case "MRTD_TD2_FRENCH_ID":
        return "td2";

    case "MRTD_TD3_PASSPORT":
    case "MRTD_TD3_VISA":
        return "passport";

    default:
        throw new Error(`Unknown document type: ${codeType}`);
    }
}

function documentTypeLabel(codeType) {
    switch (codeType) {
    case "MRTD_TD1_ID":
        return "ID (TD1)";

    case "MRTD_TD2_ID":
        return "ID (TD2)";
    case "MRTD_TD2_VISA":
        return "ID (VISA)";
    case "MRTD_TD2_FRENCH_ID":
        return "French ID (TD2)";

    case "MRTD_TD3_PASSPORT":
        return "Passport (TD3)";
    case "MRTD_TD3_VISA":
        return "Visa (TD3)";

    default:
        throw new Error(`Unknown document type: ${codeType}`);
    }
}