js实现无重复组合

var aadd = ['a', 'b', 'c'];
/**
 *
 * @param aadd  所有的数字的数组
 * @param size  需要选择几个数
 * @returns {Array}返回一个数组
 */
function jisuan(aadd, size) {
  var resultArr = [];
  deepCompute(aadd, size - 1, 0, "", resultArr);

  //console.log(resultArr);

  function deepCompute(arr, choselen, index, str) {
    for (var a = index; a < arr.length - choselen; a++) {
      if (choselen != 0) {
        deepCompute(arr, choselen - 1, a + 1, str + arr[a] + ",")
      } else {
        resultArr.push(str + arr[a])
      }
    }
  }

  return resultArr;
}

var result = [];
for (var i = 2; i <= ar.length + 1; i++) {
  result.push(jisuan(aadd, i));
}

var lastResult = [];
for (var i = 0; i < result.length; i++) {
  lastResult = lastResult.concat(result[i]);
}
console.log(lastResult);