是否有一种方法可以在JavaScript中返回两个数组之间的差异?

例如:

var a1 = ['a', 'b'];
var a2 = ['a', 'b', 'c', 'd'];

// need ["c", "d"]

当前回答

我同意@luis-sieira的解决方案

我创建了位自解释函数,便于初学者一步一步理解:

function difference(oneArr, twoArr){
  var newArr = [];
  newArr = oneArr.filter((item)=>{
      return !twoArr.includes(item)
  });
  console.log(newArr)
    let arr = twoArr.filter((item)=>{
        return !oneArr.includes(item)
     });
    newArr =  newArr.concat(arr);
  console.log(newArr)
}
difference([1, 2, 3, 5], [1, 2, 3, 4, 5])

其他回答

下面是另一个可以返回差异的解决方案,就像git diff一样:(它已经用typescript编写,如果你不使用typescript版本,只需删除类型)

/**
 * util function to calculate the difference between two arrays (pay attention to 'from' and 'to'),
 * it would return the mutations from 'from' to 'to' 
 * @param { T[] } from
 * @param { T[] } to
 * @returns { { [x in string]: boolean } } it would return the stringified version of array element, true means added,
 * false means removed
 */
export function arrDiff<T>(from: T[], to: T[]): { [x in string]: boolean } {

  var diff: { [x in string]: boolean } = {};
  var newItems: T[] = []
  diff = from.reduce((a, e) => ({ ...a, [JSON.stringify(e)]: true }), {})

  for (var i = 0; i < to.length; i++) {
    if (diff[JSON.stringify(to[i])]) {
      delete diff[JSON.stringify(to[i])]
    } else {
      newItems.push(to[i])
    }
  }

  return {
    ...Object.keys(diff).reduce((a, e) => ({ ...a, [e]: false }), {}),
    ...newItems.reduce((a, e) => ({ ...a, [JSON.stringify(e)]: true }), {})
  }
}

下面是一个用法示例:

arrDiff(['a', 'b', 'c'], ['a', 'd', 'c', 'f']) //{"b": false, "d": true, "f": true}

这是目前为止最简单的方法来得到你正在寻找的结果,使用jQuery:

var diff = $(old_array).not(new_array).get();

Diff现在包含了old_array中不在new_array中的内容

**这将根据'type'参数为任意2个数组返回一个唯一值数组,或一个重复值数组,或一个非重复值数组(difference)。**

let json1 = ['one', 'two']
let json2 = ['one', 'two', 'three', 'four']

function uniq_n_shit (arr1, arr2, type) {

  let concat = arr1.concat(arr2)
  let set = [...new Set(concat)]

  if (!type || type === 'uniq' || type === 'unique') {

    return set

  } else if (type === 'duplicate') {

    concat = arr1.concat(arr2)
    return concat.filter(function (obj, index, self) {
      return index !== self.indexOf(obj)
    })

  } else if (type === 'not_duplicate') {

    let duplicates = concat.filter(function (obj, index, self) {
      return index !== self.indexOf(obj)
    })

    for (let r = 0; r < duplicates.length; r++) {
      let i = set.indexOf(duplicates[r]);
      if(i !== -1) {
        set.splice(i, 1);
      }
    }

    return set

  }
}

console.log(uniq_n_shit(json1, json2, null)) // => [ 'one', 'two', 'three', 'four' ]
console.log(uniq_n_shit(json1, json2, 'uniq')) // => [ 'one', 'two', 'three', 'four' ]
console.log(uniq_n_shit(json1, json2, 'duplicate')) // => [ 'one', 'two' ]
console.log(uniq_n_shit(json1, json2, 'not_duplicate')) // => [ 'three', 'four' ]

对称和线性复杂度。需要ES6。

function arrDiff(arr1, arr2) {
    var arrays = [arr1, arr2].sort((a, b) => a.length - b.length);
    var smallSet = new Set(arrays[0]);

    return arrays[1].filter(x => !smallSet.has(x));
}

要从另一个数组中减去一个数组,只需使用下面的代码片段:

var a1 = ['1','2','3','4','6'];
var a2 = ['3','4','5'];

var items = new Array();

items = jQuery.grep(a1,function (item) {
    return jQuery.inArray(item, a2) < 0;
});

它将返回['1,'2','6'],这些是第一个数组中不存在的项。

因此,根据您的问题示例,以下代码是准确的解决方案:

var array1 = ["test1", "test2","test3", "test4"];
var array2 = ["test1", "test2","test3","test4", "test5", "test6"];

var _array = new Array();

_array = jQuery.grep(array2, function (item) {
     return jQuery.inArray(item, array1) < 0;
});