Validate Australian Business Number

validateABN.js

/**
 * Checks ABN for validity using the published ABN checksum algorithm.
 * @author Guy Carpenter
 * @license http://www.clearwater.com.au/code None
 * @param  {String|Number} value abn to validate
 * @return {Boolean} Is ABN Valid
 */
function validateABN (value) {

	var weights = [10, 1, 3, 5, 7, 9, 11, 13, 15, 17, 19],
		abn = value.replace(/[^\d]/g, ''),
		result = false;

	// check length is 11 digits
	if (abn.length === 11) {

		// apply ato check method
		var sum = 0,
			weight;

		for (var index = 0; index <= weights.length - 1; index++) {
			weight = weights[index];
			digit = abn[index] - (index ? 0 : 1);
			sum += weight * digit;
		}

		result = sum % 89 === 0;
	}

	return result;
}

If your ABN is anything spaced like 51 824 753 556 format, the replacer function needs a 'g' flag, or use the new replaceAll.

abn = value.replace(/[^\d]/g, '');

sample ABNs

If your ABN is anything spaced like 51 824 753 556 format, the replacer function needs a 'g' flag, or use the new replaceAll.

abn = value.replace(/[^\d]/g, '');

sample ABNs

👍

I would also use proper declarations, let and the digit variable is missing declaration.

function validateAustralianABN(value) {

    const weights = [10, 1, 3, 5, 7, 9, 11, 13, 15, 17, 19];
    let abn = value?.toString().replace(/[^\d]/g, '');
    let result = false;

    // check length is 11 digits
    if (abn?.length === 11) {

        // apply ato check method
        let sum = 0,
            weight,
            digit;

        for (let index = 0; index <= weights.length - 1; index++) {
            weight = weights[index];
            digit = abn[index] - (index ? 0 : 1);
            sum += weight * digit;
        }

        result = sum % 89 === 0;
    }

    return result;
}