我在这里读到的答案有很多问题，使得它们在实际编程应用中价值有限。

First and foremost, you're going to want to have a way to control what it means for two items in the array to be "equal". The === comparison is not going to cut it if you're trying to figure out whether to update an array of objects based on an ID or something like that, which frankly is probably one of the most likely scenarios in which you will want a diff function. It also limits you to arrays of things that can be compared with the === operator, i.e. strings, ints, etc, and that's pretty much unacceptable for grown-ups.

其次，diff操作有三种状态结果:

在第一个数组中但不在第二个数组中的元素 两个数组共用的元素 在第二个数组中但不在第一个数组中的元素

我认为这意味着你需要不少于2个循环，但我愿意接受肮脏的技巧，如果有人知道如何将其减少到一个。

这里是我拼凑的一些东西，我想强调的是，我绝对不在乎它在旧版本的Microshaft浏览器中不起作用。如果您在IE这样的较差的编码环境中工作，那么您就可以自行修改它，使其在您无法满意的限制范围内工作。

Array.defaultValueComparison = function(a, b) {
    return (a === b);
};

Array.prototype.diff = function(arr, fnCompare) {

    // validate params

    if (!(arr instanceof Array))
        arr = [arr];

    fnCompare = fnCompare || Array.defaultValueComparison;

    var original = this, exists, storage, 
        result = { common: [], removed: [], inserted: [] };

    original.forEach(function(existingItem) {

        // Finds common elements and elements that 
        // do not exist in the original array

        exists = arr.some(function(newItem) {
            return fnCompare(existingItem, newItem);
        });

        storage = (exists) ? result.common : result.removed;
        storage.push(existingItem);

    });

    arr.forEach(function(newItem) {

        exists = original.some(function(existingItem) {
            return fnCompare(existingItem, newItem);
        });

        if (!exists)
            result.inserted.push(newItem);

    });

    return result;

};

const difference = function (baseArray, arrayToCampare, callback = (a, b) => a!== b) {
  if (!(arrayToCampare instanceof Array)) {
    return baseArray;
  }
  return baseArray.filter(baseEl =>
    arrayToCampare.every(compareEl => callback(baseEl, compareEl)));
}

非常简单的解决方案与JavaScript的过滤器功能:

Var a1 = ['a'， 'b']; Var a2 = ['a'， 'b'， 'c'， 'd']; (arr1, arr2) { var newArr = []; var myArr = ar1 .concat(arr2); newArr = myArr.filter(函数(项){ return arr2.indexOf(item) < 0 || arr1.indexOf(item) < 0; })； 警报(newArr); ｝ diffArray (a1, a2);

const dbData = [{name:'ally'}, 
{name:'James'}]
const localData = [{name:'James'}] 

const diff = dbData.filter(a =>!localData.some(b => { return a.name === b.name}))

Array.prototype.difference = function(e) {
    return this.filter(function(i) {return e.indexOf(i) < 0;});
};

eg:- 

[1,2,3,4,5,6,7].difference( [3,4,5] );  
 => [1, 2, 6 , 7]

如果你不关心原始数组，编辑它们没有问题，那么这是一个更快的算法:

let iterator = arrayA.values()
let result = []
for (entryA of iterator) {
    if (!arrayB.includes(entryA)) {
        result.push(entryA)
    } else {
        arrayB.splice(arrayB.indexOf(entryA), 1) 
    }
}

result.push(...arrayB)
return result