Morning interview questions

Dear candidate,‬ ‭ First things first, we would like to thank you for taking the time to work on this skill-evaluation‬ ‭ exercise.‬ ‭ The objective of this exercise is to give us a peek into your software modeling and development‬ ‭ skills, as well as your attention to details and quality. As the saying goes:‬ ‭ " ‬‭ Professionalism is not the job‬‭ you do, it's how you do the job.‬‭ " ‬ ‭ The task:‬ ‭ Your team has been tasked with implementing a nodejs function that validates a user’s (Israeli)‬ ‭ ID number.‬ ‭ A valid ID number consists of 9 digits and adheres to the Luhn algorithm‬ ‭ (Search for it on Wiki) ‭ The following code was implemented by your peer:‬ ‭ function isValidTaxId(taxId?: string): boolean {‬ ‭ if (isEmpty(taxId))‬ ‭ return false;‬ ‭ length = taxId.length;‬ ‭ var isValid = false;‬ ‭ if (length == 9) {‬ ‭ var aggr = 0;‬ ‭ for (var i = 0; i < length; i++) {‬ ‭ var char = taxId.substr(i, 1);‬ ‭ var mul = (1 + (i % 2)) * parseInt(char);‬ ‭ if (mul >= 9) {‬ ‭ mul -= 9;‬ ‭ }‬ ‭ aggr += mul;‬ ‭ }‬ ‭ isValid = (aggr % 10 == 0);‬ ‭ }‬ ‭ return isValid;‬ ‭ }‬ ‭ function isEmpty(text?: string): boolean {‬ ‭ return text === null || typeof text === 'undefined' || text.length === 0 || (typeof text === ‬ ‭ 'string' && text.trim() === '');‬ ‭ }‬ ‭ Your tasks are as follows:‬ ‭ 1.‬‭ Review your peer’s code and provide your feedback‬ ‭ 2.‬‭ In case you’ve spotted any bugs in the implementation, please point them out and fix‬ ‭ 3.‬‭ Valid Greek ID numbers too, adhere to‬‭ Luhn algorithm‬‭ but they consist of‬‭ exactly 10‬ ‭ digits. Extend the code to support the validation of both Israeli and Greek ID numbers‬ ‭ based on the user’s locale.‬ ‭ 4.‬‭ Valid Bulgarian ID numbers too, adhere to‬‭ Luhn algorithm‬‭ but they consist of‬‭ exactly 8‬‭ digits‬ ‭ and the sum of the first two digits must be an odd number. Extend the code to support‬ ‭ Bulgarian ID numbers.‬ ‭ 5.‬‭ How would you unit test the code? Please specify the tests you would implement.‬ ‭ Thank you!‬

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