martijnluinstra/iban.js

## iban.js
/**
 * Javascript Generator for Dutch IBANs.
 * Demo: projects.martijnluinstra.nl/iban/
 * Dependencies: https://github.com/MikeMcl/bignumber.js/
 *
 * Copyright (c) 2017 - Martijn Luinstra
 */

/**
 * Converts IBAN to the decimal representation used for validation
 */
function ibanToNumber(iban) {
    var code = iban.slice(4) + iban.slice(0,4);
    code = code.toUpperCase();
    var number = '';
    for (var idx = 0; idx < code.length; idx++)
        if (isNaN(code.charAt(idx)))
            number += code.charCodeAt(idx) - 55;
        else
            number += code.charAt(idx);
    return new BigNumber(number);
}

/**
 * Validates IBAN based on checksum
 */
function validateIban(iban) {
    return ibanToNumber(iban).mod(97).equals(1);
}

/**
 * Generates elfproef-valid account number with based on numberic string
 */
function generateAccountNumber(unchecked) {
    var total = 0
    for (var idx=0; idx < unchecked.length; idx ++)
        total += parseInt(unchecked.charAt(idx)) * (unchecked.length - idx + 1);
    var check = 11 - (total % 11)
    if (check > 0 && check < 10)
        return unchecked + check.toString();
    // Did not find a number that passes the elfproef, increase unchecked and try again
    return generateAccountNumber((parseInt(unchecked) + 1).toString());
}

/**
 * Generates realistic Dutch IBAN based on seed and (list of) bank code(s)
 */
function generateIban(seed, bankCode=null, country='NL', accountLength=9) {
    var codes = seed.toUpperCase().split('').map(x => x.charCodeAt(0));
    var number = codes.reduce((prod, value, idx) => prod.times(value + idx) , new BigNumber(1));
    number = number.toFixed().replace(/0+$/,'');

    var account = generateAccountNumber(number.slice(0, accountLength - 1));
    account = account.padStart(accountLength + 1, '0');

    if (!bankCode)
        bankCode = 'BANK';
    else if (bankCode instanceof Array) {
        let idx = (number.charCodeAt(0) * number.charCodeAt(number.length - 1))  % bankCode.length;
        bankCode = bankCode[idx];
    }

    var remainder = ibanToNumber(country + '00' + bankCode + account).mod(97);
    check = (98 - remainder).toString().padStart(2, '0');

    return country + check + bankCode + account;
}

## index.html
<!--
Javascript Generator for Dutch IBANs.
Demo: projects.martijnluinstra.nl/iban/
Dependencies: https://github.com/MikeMcl/bignumber.js/

Copyright (c) 2017 Martijn Luinstra
-->
<!DOCTYPE html>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <meta name="mobileoptimized" content="0">
        <title>IBAN</title>
        <style>
            body {
                font-family: sans-serif;
            }

            h1 {
                color: #8080ff;
            }

            label {
                display: inline-block;
                width: 4em;
                font-weight: bold;
            }

            a,
            a:hover,
            a:visited,
            a:focus {
                color: #8080ff;
                text-decoration: none;
            }

            a:hover,
            a:focus {
                text-decoration: underline;
            }

            .page {
                max-width: 35em;
                margin: 0 auto;
            }

            p.credits {
                color: #999;
                font-size: 65%;
            }
        </style>
    </head>
    <body>
        <div class="page">
            <h1>IBAN Generator</h1>
            <p>
                This tool generates a consistent and realistic Dutch IBAN for a seed. The resulting IBAN passes all IBAN validators that don't check whether the bank actually exists. The account number part (BBAN) of the generated IBANs satisfies the &ldquo;elfproef&rdquo; checksum for Dutch bank account numbers.
            </p>
            <p>
                <label for="seed">Seed</label>
                <input type="text" id="seed" name="seed" placeholder="Enter seed…">
            </p>
            <p>
                <label for="iban">IBAN</label>
                <input type="text" id="iban" name="iban" placeholder="…to generate IBAN" readonly>
            </p>
            <p class="credits">Created by <a href="https://www.martijnluinstra.nl/">Martijn Luinstra</a></p>
        </div>
        <script src="bignumber.js"></script>
        <script src="iban.js"></script>
        <script>
            var el = document.getElementById('seed');
            var target = document.getElementById('iban');
            el.addEventListener('keyup', evt => {
                if (el.value !== '')
                    target.value = generateIban(el.value);
                else
                    target.value = '';
            });
        </script>
    </body>
</html>
	/**
	* Javascript Generator for Dutch IBANs.
	* Demo: projects.martijnluinstra.nl/iban/
	* Dependencies: https://github.com/MikeMcl/bignumber.js/
	*
	* Copyright (c) 2017 - Martijn Luinstra
	*/

	/**
	* Converts IBAN to the decimal representation used for validation
	*/
	function ibanToNumber(iban) {
	var code = iban.slice(4) + iban.slice(0,4);
	code = code.toUpperCase();
	var number = '';
	for (var idx = 0; idx < code.length; idx++)
	if (isNaN(code.charAt(idx)))
	number += code.charCodeAt(idx) - 55;
	else
	number += code.charAt(idx);
	return new BigNumber(number);
	}

	/**
	* Validates IBAN based on checksum
	*/
	function validateIban(iban) {
	return ibanToNumber(iban).mod(97).equals(1);
	}

	/**
	* Generates elfproef-valid account number with based on numberic string
	*/
	function generateAccountNumber(unchecked) {
	var total = 0
	for (var idx=0; idx < unchecked.length; idx ++)
	total += parseInt(unchecked.charAt(idx)) * (unchecked.length - idx + 1);
	var check = 11 - (total % 11)
	if (check > 0 && check < 10)
	return unchecked + check.toString();
	// Did not find a number that passes the elfproef, increase unchecked and try again
	return generateAccountNumber((parseInt(unchecked) + 1).toString());
	}

	/**
	* Generates realistic Dutch IBAN based on seed and (list of) bank code(s)
	*/
	function generateIban(seed, bankCode=null, country='NL', accountLength=9) {
	var codes = seed.toUpperCase().split('').map(x => x.charCodeAt(0));
	var number = codes.reduce((prod, value, idx) => prod.times(value + idx) , new BigNumber(1));
	number = number.toFixed().replace(/0+$/,'');

	var account = generateAccountNumber(number.slice(0, accountLength - 1));
	account = account.padStart(accountLength + 1, '0');

	if (!bankCode)
	bankCode = 'BANK';
	else if (bankCode instanceof Array) {
	let idx = (number.charCodeAt(0) * number.charCodeAt(number.length - 1)) % bankCode.length;
	bankCode = bankCode[idx];
	}

	var remainder = ibanToNumber(country + '00' + bankCode + account).mod(97);
	check = (98 - remainder).toString().padStart(2, '0');

	return country + check + bankCode + account;
	}
	<!--
	Javascript Generator for Dutch IBANs.
	Demo: projects.martijnluinstra.nl/iban/
	Dependencies: https://github.com/MikeMcl/bignumber.js/

	Copyright (c) 2017 Martijn Luinstra
	-->
	<!DOCTYPE html>
	<html>
	<head>
	<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1">
	<meta name="mobileoptimized" content="0">
	<title>IBAN</title>
	<style>
	body {
	font-family: sans-serif;
	}

	h1 {
	color: #8080ff;
	}

	label {
	display: inline-block;
	width: 4em;
	font-weight: bold;
	}

	a,
	a:hover,
	a:visited,
	a:focus {
	color: #8080ff;
	text-decoration: none;
	}

	a:hover,
	a:focus {
	text-decoration: underline;
	}

	.page {
	max-width: 35em;
	margin: 0 auto;
	}

	p.credits {
	color: #999;
	font-size: 65%;
	}
	</style>
	</head>
	<body>
	<div class="page">
	<h1>IBAN Generator</h1>
	<p>
	This tool generates a consistent and realistic Dutch IBAN for a seed. The resulting IBAN passes all IBAN validators that don't check whether the bank actually exists. The account number part (BBAN) of the generated IBANs satisfies the “elfproef” checksum for Dutch bank account numbers.
	</p>
	<p>
	<label for="seed">Seed</label>
	<input type="text" id="seed" name="seed" placeholder="Enter seed…">
	</p>
	<p>
	<label for="iban">IBAN</label>
	<input type="text" id="iban" name="iban" placeholder="…to generate IBAN" readonly>
	</p>
	<p class="credits">Created by <a href="https://www.martijnluinstra.nl/">Martijn Luinstra</a></p>
	</div>
	<script src="bignumber.js"></script>
	<script src="iban.js"></script>
	<script>
	var el = document.getElementById('seed');
	var target = document.getElementById('iban');
	el.addEventListener('keyup', evt => {
	if (el.value !== '')
	target.value = generateIban(el.value);
	else
	target.value = '';
	});
	</script>
	</body>
	</html>