JS - 计算两个数组的交集、差集、并集、补集

不适用set做法

var a = [1,2,3,4,5]
var b = [2,4,6,8,10]
//交集
var c = a.filter(function(v){ return b.indexOf(v) > -1 })
//差集
var d = a.filter(function(v){ return b.indexOf(v) == -1 })
//补集
var e = a.filter(function(v){ return !(b.indexOf(v) > -1) })
 .concat(b.filter(function(v){ return !(a.indexOf(v) > -1)}))
//并集
var f = a.concat(b.filter(function(v){ return !(a.indexOf(v) > -1)}));
console.log("数组a：", a);
console.log("数组b：", b);
console.log("a与b的交集：", c);
console.log("a与b的差集：", d);
console.log("a与b的补集：", e);
console.log("a与b的并集：", f); 

使用set的做法

var a = [1,2,3,4,5]
var b = [2,4,6,8,10]
console.log("数组a：", a);
console.log("数组b：", b);
var sa = new Set(a);
var sb = new Set(b);
// 交集
let intersect = a.filter(x => sb.has(x));
// 差集
let minus = a.filter(x => !sb.has(x));
// 补集
let complement  = [...a.filter(x => !sb.has(x)), ...b.filter(x => !sa.has(x))];
// 并集
let unionSet = Array.from(new Set([...a, ...b]));
//  Array.from可以使用...代替
[...new Set([...a, ...b])]
console.log("a与b的交集：", intersect);
console.log("a与b的差集：", minus);
console.log("a与b的补集：", complement);
console.log("a与b的并集：", unionSet);