DCI_Calculator.js

/*
 * Magic: The Gathering - DCI Calculator (for older DCI numbers to be converted)
 *
 * ORIGINAL: https://pastebin.com/PG59ZsJ7
 * CLONED because I want to make sure it stays alive for when i need it.
 * DATE: 2016-07-28
*/

var primes = [43, 47, 53, 71, 73, 31, 37, 41, 59, 61, 67, 29]
var dcinumber = "1076753660" /* EDIT it as needed */

var sum   = 0
var cdsum = 0
for (i = 0; i < dcinumber.length-1; i++){
    sum += parseInt(dcinumber[i+1])*primes[i]
}
for (i = 0; i < dcinumber.length; i++){
    cdsum += parseInt(dcinumber[i])*primes[i]
}

console.log("Next check digit would be " + (1 + Math.floor(cdsum / 10) % 9))

var valid = (1 + Math.floor(sum / 10) % 9) == parseInt(dcinumber[0])

console.log(valid)