Complementary DNA

❓ Complementary DNA

Q. Deoxyribonucleic acid (DNA) is a chemical found in the nucleus of cells and carries the "instructions" for the development and functioning of living organisms.

If you want to know more: http://en.wikipedia.org/wiki/DNA

In DNA strings, symbols "A" and "T" are complements of each other, as "C" and "G". Your function receives one side of the DNA (string, except for Haskell); you need to return the other complementary side. DNA strand is never empty or there is no DNA at all (again, except for Haskell).

More similar exercise are found here: http://rosalind.info/problems/list-view/ (source)

Example: (input --> output)

"ATTGC" --> "TAACG"
"GTAT" --> "CATA"

✔ Solution

function DNAStrand(dna) {
  //your code here
  //   let sequence = {
  //     A: "T",
  //     T: "A",
  //     G: "C",
  //     C: "G",
  //   };
  //   return dna.replace(/A|T|G|C/g, function (matched) {
  //     return sequence[matched];
  //   });
  var dnaArr = dna.split("");
  for (var i = 0; i < dnaArr.length; i++) {
    if (dnaArr[i] === "A") {
      dnaArr[i] = "T";
    } else if (dnaArr[i] === "T") {
      dnaArr[i] = "A";
    } else if (dnaArr[i] === "C") {
      dnaArr[i] = "G";
    } else if (dnaArr[i] === "G") {
      dnaArr[i] = "C";
    }
  }
  var lastValue = dnaArr.join("");
  return lastValue;
}