将两个数组的值合并为object

function mergeArrays(array1, array2) {
  var result = {};

  for (var i = 0; i < array1.length; i++) {
    result[array1[i]] = i;
  }

  for (var j = 0; j < array2.length; j++) {
    result[array2[j]] = j;
  }

  return result;
}

var array1 = ['a', 'b'];
var array2 = ['c', 'd'];

var mergedObject = mergeArrays(array1, array2);
console.log(mergedObject);

{
  'a': 0,
  'b': 1,
  'c': 0,
  'd': 1
}