简介

集合是什么

• 一种无序且唯一的数据结构。

• ES6中有集合，名为Set

• 集合的常用操作：去重、判断某元素是否在集合中、求交集...

Codeing Part

// 去重
const arr = [1, 1, 2, 2];
const arr2 = [...new Set(arr)];

// 判断元素是否在集合中
const set = new Set(arr);
const has = set.has(3);

// 求交集
const set2 = new Set([2, 3]);
const set3 = new Set([...set].filter(item => set2.has(item)));

es6中的Set

let mySet = new Set();

mySet.add(1);
mySet.add(5);
mySet.add(5);
mySet.add('some text');
let o = { a: 1, b: 2 };
mySet.add(o);
mySet.add({ a: 1, b: 2 });

const has = mySet.has(o);

mySet.delete(5);

for(let [key, value] of mySet.entries()) console.log(key, value);

const myArr = Array.from(mySet);

const mySet2 = new Set([1,2,3,4]);

const intersection = new Set([...mySet].filter(x => mySet2.has(x)));
const difference = new Set([...mySet].filter(x => !mySet2.has(x)));