freeCodeCamp

2.5 KiB

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title	id	challengeType
SEDOLs	59d9c6bc214c613ba73ff012	5

Description

Task:

For each number list of 6-digit SEDOLs, calculate and append the checksum digit.

That is, given the input string on the left, your function should return the corresponding string on the right:

<pre>
 710889 => 7108899
 B0YBKJ => B0YBKJ7
 406566 => 4065663
 B0YBLH => B0YBLH2
 228276 => 2282765
 B0YBKL => B0YBKL9
 557910 => 5579107
 B0YBKR => B0YBKR5
 585284 => 5852842
 B0YBKT => B0YBKT7
 B00030 => B000300
</pre>

Check also that each input is correctly formed, especially with respect to valid characters allowed in a SEDOL string. Your function should return null on invalid input.

Instructions

Tests

tests:
  - text: <code>sedol</code> is a function.
    testString: 'assert(typeof sedol === "function", "<code>sedol</code> is a function.");'
  - text: <code>sedol('a')</code> should return null.")
    testString: 'assert(sedol("a") === null, "<code>sedol("a")</code> should return null.");'
  - text: <code>sedol('710889')</code> should return '7108899'.")
    testString: 'assert(sedol("710889") === "7108899", "<code>sedol("710889")</code> should return "7108899".");'
  - text: <code>sedol('BOATER')</code> should return null.")
    testString: 'assert(sedol("BOATER") === null, "<code>sedol("BOATER")</code> should return null.");'
  - text: <code>sedol('228276')</code> should return '2282765'.")
    testString: 'assert(sedol("228276") === "2282765", "<code>sedol("228276")</code> should return "2282765".");'

Challenge Seed

function sedol (input) {
  // Good luck!
  return true;
}

Solution

function sedol(input) {
  const checkDigit = sedolCheckDigit(input);
  if (checkDigit !== null) {
    return input + checkDigit;
  }
  return null;
}

const weight = [1, 3, 1, 7, 3, 9, 1];
function sedolCheckDigit(char6) {
  if (char6.search(/^[0-9BCDFGHJKLMNPQRSTVWXYZ]{6}$/) === -1) {
    return null;
  }

  let sum = 0;
  for (let i = 0; i < char6.length; i++) {
    sum += weight[i] * parseInt(char6.charAt(i), 36);
  }
  const check = (10 - (sum % 10)) % 10;
  return check.toString();
}

2.5 KiB Raw Blame History