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

bonfire-dna-pairing#.js

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

function pair(str) {
  var returnArr = [];
  for(var i = 0; i < str.length; i++){
    
    switch(str.charAt(i)){
      case "A":
        returnArr.push(["A", "T"]);
        break;
      case "T":
        returnArr.push(["T", "A"]);
        break;
      case "C":
        returnArr.push(["C", "G"]);
        break;
      case "G":
        returnArr.push(["G", "C"]);
        break;
      default:
        console.log("Error: Not a valid Base Pair");
    }
    
  }
  return returnArr;
}

pair("GCG");