1234567891011121314151617181920212223242526272829303132
/** * Private `concat` function to merge two array-like objects. * * @private * @param {Array|Arguments} [set1=[]] An array-like object. * @param {Array|Arguments} [set2=[]] An array-like object. * @return {Array} A new, merged array. * @example * *      _concat([4, 5, 6], [1, 2, 3]); //=> [4, 5, 6, 1, 2, 3] */export default function _concat(set1, set2) {  set1 = set1 || [];  set2 = set2 || [];  var idx;  var len1 = set1.length;  var len2 = set2.length;  var result = [];
  idx = 0;  while (idx < len1) {    result[result.length] = set1[idx];    idx += 1;  }  idx = 0;  while (idx < len2) {    result[result.length] = set2[idx];    idx += 1;  }  return result;}