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

根据之前的答案…取决于你是想要一个高效的还是“漂亮的联机”解决方案。

一般有三种方法……

"manual iterative" (using indexOf) - naive with O(n2) complexity (slow) var array_diff_naive = function(a,b){ var i, la = a.length, lb = b.length, res = []; if (!la) return b; else if (!lb) return a; for (i = 0; i < la; i++) { if (b.indexOf(a[i]) === -1) res.push(a[i]); } for (i = 0; i < lb; i++) { if (a.indexOf(b[i]) === -1) res.push(b[i]); } return res; } "abstract iterative" (using filter and concat library methods) - syntactic sugar for manual iterative (looks nicer, still sucks) var array_diff_modern = function(a1,a2){ return a1.filter(function(v) { return !a2.includes(v); } ) .concat(a2.filter(function(v) { return !a1.includes(v);})); } "using hashtable" (using object keys) - much more efficient - only O(n), but has slightly limited range of input array values var array_diff_hash = function(a1,a2){ var a = [], diff = []; for (var i = 0; i < a1.length; i++) { a[a1[i]] = true; } for (var i = 0; i < a2.length; i++) { if (a[a2[i]]) { delete a[a2[i]]; } else { a[a2[i]] = true; } } for (var k in a) { diff.push(k); } return diff; }

在jsperf上可以看到 https://jsperf.com/array-diff-algo

其他回答

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

一个衬垫

const unique = (a) => [...new Set(a)]; const uniqueBy = (x,f)=>Object.values(x.reduce((a,b)=>((a[f(b)]=b),a),{})); const intersection = (a, b) => a.filter((v) => b.includes(v)); const diff = (a, b) => a.filter((v) => !b.includes(v)); const symDiff = (a, b) => diff(a, b).concat(diff(b, a)); const union = (a, b) => diff(a, b).concat(b); const a = unique([1, 2, 3, 4, 5, 5]); console.log(a); const b = [4, 5, 6, 7, 8]; console.log(intersection(a, b), diff(a, b), symDiff(a, b), union(a, b)); console.log(uniqueBy( [ { id: 1, name: "abc" }, { id: 2, name: "xyz" }, { id: 1, name: "abc" }, ], (v) => v.id )); const intersectionBy = (a, b, f) => a.filter((v) => b.some((u) => f(v, u))); console.log(intersectionBy( [ { id: 1, name: "abc" }, { id: 2, name: "xyz" }, ], [ { id: 1, name: "abc" }, { id: 3, name: "pqr" }, ], (v, u) => v.id === u.id )); const diffBy = (a, b, f) => a.filter((v) => !b.some((u) => f(v, u))); console.log(diffBy( [ { id: 1, name: "abc" }, { id: 2, name: "xyz" }, ], [ { id: 1, name: "abc" }, { id: 3, name: "pqr" }, ], (v, u) => v.id === u.id ));

打印稿

操场上的链接

const unique = <T>(array: T[]) => [...new Set(array)];


const intersection = <T>(array1: T[], array2: T[]) =>
  array1.filter((v) => array2.includes(v));


const diff = <T>(array1: T[], array2: T[]) =>
  array1.filter((v) => !array2.includes(v));


const symDiff = <T>(array1: T[], array2: T[]) =>
  diff(array1, array2).concat(diff(array2, array1));


const union = <T>(array1: T[], array2: T[]) =>
  diff(array1, array2).concat(array2);


const intersectionBy = <T>(
  array1: T[],
  array2: T[],
  predicate: (array1Value: T, array2Value: T) => boolean
) => array1.filter((v) => array2.some((u) => predicate(v, u)));


const diffBy = <T>(
  array1: T[],
  array2: T[],
  predicate: (array1Value: T, array2Value: T) => boolean
) => array1.filter((v) => !array2.some((u) => predicate(v, u)));


const uniqueBy = <T>(
  array: T[],
  predicate: (v: T, i: number, a: T[]) => string
) =>
  Object.values(
    array.reduce((acc, value, index) => {
      acc[predicate(value, index, array)] = value;
      return acc;
    }, {} as { [key: string]: T })
  );
function diffArray(newArr, oldArr) {
    var newSet = new Set(newArr)
    var diff = []
    oldArr.forEach((a) => {
        if(!newSet.delete(a))diff.push(a)
    })
    return diff.concat(Array.from(newSet)) 
}

/ / es6方法

function diff(a, b) {
  var u = a.slice(); //dup the array
  b.map(e => {
    if (u.indexOf(e) > -1) delete u[u.indexOf(e)]
    else u.push(e)   //add non existing item to temp array
  })
  return u.filter((x) => {return (x != null)}) //flatten result
}

只是修整字符串以确保....空格不会影响差异

function arr_diff(a1, a2) {
    var a=[], diff=[];
    for(var i=0;i<a1.length;i++)
        a[a1[i]]=true;
    for(var i=0;i<a2.length;i++)
        if(a[a2[i].trim()]) delete a[a2[i].trim()];
    else a[a2[i].trim()]=true;
    for(var k in a)
        diff.push(k);
    return diff;
}