http://www.freecodecamp.com/minsooshin 's solution for Bonfire: DNA Pairing

bonfire-dna-pairing.js

// Bonfire: DNA Pairing
// Author: @minsooshin
// Challenge: http://www.freecodecamp.com/challenges/bonfire-dna-pairing
// Learn to Code at Free Code Camp (www.freecodecamp.com)

function pair(str) {
  var pairing = {
        "A": "T",
        "T": "A",
        "C": "G",
        "G": "C"
      },
      final = [];
  final = str.split('').map(function(val) {
    var arr = [];
    arr.push(val, pairing[val]);
    return arr;
  });
  
  return final;
}

pair("GCG");