算法 - JavaScript数组系列问题：数组差集-PHP 중국어 네트워크 Q&A

JavaScript求出两个数组的差集，下面是我实现的方法

function arrayDiffSet(a, b) { if ((!a || !a.length) && (b && b.length)) { return b } else if ((!b || !b.length) && (a && a.length)) { return a } var aMap = {}, _aMap = {}, _bMap = {}; for (var i = 0, length = a.length; i < length; i++) { aMap[a[i]] = _aMap[a[i]] = true; } for (var i = 0, length = b.length; i < length; i++) { if (aMap[b[i]]) { delete _aMap[b[i]]; } else { _bMap[b[i]] = true; } } return { a: Object.keys(_aMap), b: Object.keys(_bMap) } } function generateRandomArray(length, range) { var result = []; for (var i = 0; i < length; i++) { result[result.length] = Math.floor(Math.random() * range); } return result } var a = generateRandomArray(5, 10); var b = generateRandomArray(10, 10); console.log('a', a); console.log('b', b); console.time('start'); console.log(arrayDiffSet(a, b)); console.timeEnd('start');

----------但是这个方法还有下面两点：
1、扩展性差，如果我需要返回的差集不去重，那需要再重新写一个方法；
2、没有办法对对象数组求差集；

所以在这里想问问各位大神有没有更优的解决方案

var a = generateRandomArray(5, 10); var b = generateRandomArray(10, 10); // 不去重 var result = { a: a.filter(el => !b.includes(el)), b: b.filter(el => !a.includes(el)) } // 去重 var result2 = { a: [...new Set(a)].filter(el => !b.includes(el)), b: [...new Set(b)].filter(el => !a.includes(el)) } // 合并一下 function diffSet(a, b, noDup) { if (noDup) { a = [...new Set(a)]; b = [...new Set(b)]; } return { a: a.filter(el => !b.includes(el)), b: b.filter(el => !a.includes(el)) } }

// 不去重 // 使用indexOf代替includes a.filter(function(el){ return b.indexOf(el) == -1; }); // 去重 // 引入index先对a自身去重 a.filter(function(el, idx){ return a.indexOf(el) == idx && b.indexOf(el) == -1; });

/** * 新方法 * @param {Object} a * @param {Object} b * @param {Object} isDup 是否不去重（默认去重） */ function arrayDiffSet(a, b, isDup) { var al = a.length, bl = b.length; if ((!a || !al) && (b && bl)) { return b } else if ((!b || !bl) && (a && al)) { return a } var i = 0, aMap = {}, _aMap = {}, _bMap = {}, _a = [], _b = [], temp; for (i = 0; i < al; i++) { temp = a[i]; aMap[temp] = true; !_aMap[temp] ? _aMap[temp] = [] : ''; _aMap[temp][_aMap[temp].length] = temp; } for (i = 0; i < bl; i++) { temp = b[i]; if (aMap[temp]) { delete _aMap[temp]; } else { _b[_b.length] = temp; _bMap[temp] = true; } } if (isDup) { for (var item in _aMap) { _a = _a.concat(_aMap[item]); } return { a: _a, b: _b } } return { a: Object.keys(_aMap), b: Object.keys(_bMap) } } function generateRandomArray(length, range) { var result = []; for (var i = 0; i < length; i++) { result[result.length] = Math.floor(Math.random() * range); } return result } var a = generateRandomArray(1000, 1000); var b = generateRandomArray(1000, 1000); console.log(a); console.log(b); console.time('start'); console.log(arrayDiffSet(a, b, true)); console.timeEnd('start');