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added luhn's checksum algorithm

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Alex Brown
2018-10-21 18:57:20 -05:00
parent 31d5467ada
commit f44fdc7dd0
2 changed files with 23 additions and 0 deletions
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16
Checksums/luhn.js Normal file
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function luhn(card_number) {
var sum_of_odds = 0;
var sum_of_evens = 0;
for (var i = 15; i > 0; i-=2) {
sum_of_odds += parseInt(card_number[i]);
}
for (var i = 14; i > -1; i-=2) {
var current_number = parseInt(card_number[i]);
if (parseInt(card_number[i])*2 > 9) {
sum_of_evens += (i*2)-9;
} else {
sum_of_evens += i*2;
}
}
return 0 === ((sum_of_odds + sum_of_evens) % 10);
}