js 数组交集，差集，并集

1，直接使用 filter、concat 来计算

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);

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);
 
 
方法二：使用 ES6 语法实现
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]));
 
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);

3.原型方式

/数组功能扩展
//数组迭代函数
Array.prototype.each = function(fn){
  fn = fn || Function.K;
   var a = [];
   var args = Array.prototype.slice.call(arguments, 1);
   for(var i = 0; i < this.length; i++){
       var res = fn.apply(this,[this[i],i].concat(args));
       if(res != null) a.push(res);
   }
   return a;
};
 
//数组是否包含指定元素
Array.prototype.contains = function(suArr){
  for(var i = 0; i < this.length; i ++){
      if(this[i] == suArr){
          return true;
      }
   }
   return false;
}
 
//不重复元素构成的数组
Array.prototype.uniquelize = function(){
   var ra = new Array();
   for(var i = 0; i < this.length; i ++){
      if(!ra.contains(this[i])){
          ra.push(this[i]);
      }
   }
   return ra;
};
 
//两个数组的交集
Array.intersect = function(a, b){
   return a.uniquelize().each(function(o){return b.contains(o) ? o : null});
};
 
//两个数组的差集
Array.minus = function(a, b){
   return a.uniquelize().each(function(o){return b.contains(o) ? null : o});
};
 
//两个数组的补集
Array.complement = function(a, b){
   return Array.minus(Array.union(a, b),Array.intersect(a, b));
};
 
//两个数组并集
Array.union = function(a, b){
   return a.concat(b).uniquelize();
};

4.数组对象类似

let students = [
		{
			name: "xxx",
			grade: 80,
			show: true
		},
		{
			name: "yyy",
			grade: 50,
			show: false
		}
	]
	let students4 = [
		{
			name: "xxx",
			grade: 80,
			show: true
		},
		{
			name: "zzz",
			grade: 80,
			show: true
		},
		{
			name: "yyy",
			grade: 50,
			show: false
		}
	]
	let arr8 = [...students].filter(x => [...students4].some(y => y.name === x.name));
	console.log(arr8)