create_pattern.js

function combinationLoop(list, choose, callback) {
  (function loop(result, nest, index, length) {
    while (index <= length + nest - choose) {
      (nest === 0 ? (result = []) : result)[nest] = list[index++];
      if (nest < choose - 1) {
        loop(result, nest + 1, index, length);
      } else {
        callback(result.concat()); // 状況に応じて不要
      }
    }
  })(null, 0, 0, list.length);
}

combinationLoop(['A', 'B', 'C', 'D', 'E'], 3, function(list) {
  console.log(list);
});