Set 元素不会重复 let list = new Set() list.add(5) list.add(7) console.log(list) // 长度 console.log(list.size) let arr = [1, 2, 3, 4, 5] let list = new Set(arr) console.log(list) 去重 let arr = [1, 2, 3, 4, 2, 3, 4, 3, 4] let list = new Set(arr) console.log(list) 增删查改 let arr = [‘add‘, ‘delete‘, ‘clear‘, ‘has‘] let list = new Set(arr) // 是否在数组里 console.log(list.has(‘add‘)) // 删除 list.delete(‘add‘) console.log(list) // 清空 list.clear() console.log(list) let arr = [33, 11, 35, 78, 99] let list = new Set(arr) for (let key of list.keys()) { console.log(key) } for (let value of list.values()) { console.log(value) } for (let value of list) { console.log(value) } for (let [key, value] of list.entries()) { console.log(key, value) } list.forEach(item => { return console.log(item) }) 和Set增删查改循环一样 // 区别:weakList只能接收对象 // 只具有 add has delete方法 let weakList = new WeakSet() let obj = { name: ‘ronle‘ } weakList.add(obj) console.log(weakList) console.log(weakList.has(obj)) Map(增加值是用set方法,而不是add) let map = new Map() let key = [‘123‘] map.set(key, ‘456‘) console.log(map) // 获取对应key的值 456 console.log(map.get(key)) let map = new Map([[‘a‘, ‘123‘], [‘b‘, 456]]) map.set(‘c‘, ‘789‘) for (let [key, value] of map.entries()) { console.log(key, value) } console.log(map.size) console.log(map.has(‘b‘)) console.log(map.delete(‘a‘)) console.log(map.clear()) let weakMap = new WeakMap() let obj = {} // 只具有set get has delete方法 weakMap.set(obj, 123) console.log(weakMap) console.log(weakMap.get(obj))
原文地址:https://www.cnblogs.com/ronle/p/11494602.html
时间: 2024-11-03 10:31:45