Diff Two Arrays - freeCodeCamp

比较两个数组，然后返回一个新数组，该数组的元素为两个给定数组中所有独有的数组元素。
换言之，返回两个数组的差异。

这是一些对你有帮助的资源:

Comparison Operators
Array.slice()
Array.filter()
Array.indexOf()
Array.concat()

验证条件

• diff([1, 2, 3, 5], [1, 2, 3, 4, 5]) 应该返回一个数组。
• ["diorite", "andesite", "grass", "dirt", "pink wool", "dead shrub"], ["diorite", "andesite", "grass", "dirt", "dead shrub"] 应该返回 ["pink wool"]。
• ["andesite", "grass", "dirt", "pink wool", "dead shrub"], ["diorite", "andesite", "grass", "dirt", "dead shrub"] 应该返回 ["diorite", "pink wool"]。
• ["andesite", "grass", "dirt", "dead shrub"], ["andesite", "grass", "dirt", "dead shrub"] 应该返回 []。
• [1, 2, 3, 5], [1, 2, 3, 4, 5] 应该返回 [4]。
• [1, "calf", 3, "piglet"], [1, "calf", 3, 4] 应该返回 ["piglet", 4]。
• [], ["snuffleupagus", "cookie monster", "elmo"] 应该返回 ["snuffleupagus", "cookie monster", "elmo"]。
• [1, "calf", 3, "piglet"], [7, "filly"] 应该返回 [1, "calf", 3, "piglet", 7, "filly"]。

代码

function diff(arr1, arr2) {
  var newArr = [];
  // Same, same; but different.
  var a1 = [];
  for(var i=0;i< arr1.length;i++){
    if(arr2.indexOf(arr1[i]) ==-1){
      newArr.push(arr1[i]);
    }
  }
  for(var index=0; index < arr2.length;index++){
    if(arr1.indexOf(arr2[index]) ==-1){
      a1.push(arr2[index]);
    }
  }
  return a1.concat(newArr);
}

diff(["andesite", "grass", "dirt", "pink wool", "dead shrub"], ["diorite", "andesite", "grass", "dirt", "dead shrub"]);

其它方法

function diff(arr1, arr2) {
  var newArr = [];
  // Same, same; but different.
  newArr = arr1.filter(function(v){
   return arr2.indexOf(v) == -1;
  }).concat(arr2.filter(function(v){
   return arr1.indexOf(v) == -1;
  }));
  return newArr;
}

diff([1, "calf", 3, "piglet"], [1, "calf", 3, 4]);

es6

function diff(arr1, arr2) {
  var newArr = [];
  // Same, same; but different.
  newArr = arr1.filter( (v) => {
    return arr2.indexOf(v) == -1;
  }).concat( arr2.filter( (v) => {
    return arr1.indexOf(v) == -1;
  }));
  return newArr;
}

diff([1, "calf", 3, "piglet"], [7, "filly"]);