配列

[
  ["A","B","C"],
  ["1","2","3"]
]

を

"A1","A2","A3","B1","B2","B3","C1","C2","C3"

にする方法

直積というらしい。wikipedia 直積集合

  var directProduct = function (arr) {
    var ans = [];
    var mul = function (a,b) {
      var ret = [];
      for(var i in a) {
        for(var j in b) {
          ret.push(a[i] + b[j]);
        }
      }
      return ret;
    }
    for(var i in arr) {
      if(ans[0] == undefined) {
        ans = qArr[0];
      }else{
        ans = mul(ans,qArr[i]);
      }
    }
    return ans;
  }

  console.log( directProduct(qArr).join(",") );