Typescript的Set与Map数据结构使用

//Set,成员唯一,没有重复
let myset = new Set();
[1,2,3,4,5,6,7,8,9,0].forEach(x=>myset.add(x));
console.log(myset,myset.keys(),myset.values(),myset.entries(),myset.size);
let s = new Set([1,2,3,4,4,5,5,6,6,6]);//重复的数据只取一个
console.log(s);

let s1 = new Set();
s1.add('a');
s1.add('b');
s1.add(1);
s1.add(2);
s1.add(3);
console.log(s1);
console.log(s1.has('b'),s1.has(2));
s1.delete(2);
s1.delete('b');
console.log(s1,s1.has('b'),s1.has('2'));
s1.clear();
console.log(s1);

//Set转换数组
let s2 = new Set([1,2,3,4,5,6,7,8,9,0]);
console.log('Set:',s2);
let arr = Array.from(s2);
console.log('Array:',arr);
//数组去重实现
let s3= [1,2,3,3,3,4,5,5,6,6,7,7,7,8,9,9,9,0,0,0];
console.log(s3);
let tmpSet = new Set(s3);
console.log(tmpSet);
s3=Array.from(tmpSet);
console.log(s3);
//...运算符与Set简化去重
let newSet = new Set( [1,2,3,3,4,4,4,5,5]);
// @ts-ignore
console.log([...newSet]);

let s4 = new Set([1,2,3]);
// @ts-ignore
console.log([...s4].map(x=>x*3));
// @ts-ignore
console.log([...s4].map(x=>x*3).filter(x=>x>3));

let s5 = new Set([1,2,3]);
let s6 = new Set([4,5,6]);
// @ts-ignore
console.log(new Set([...s5,...s6]));

let s7 = new Set([1,2,3]);
let s8 = new Set([1,3,6]);
// @ts-ignore
console.log(new Set([...s7].filter(x=>s8.has(x))));//查找两个Set重复出现的元素
// @ts-ignore
console.log(new Set([...s7].filter(x=>!s8.has(x))));//查找两个Set没重复出现的元素
// @ts-ignore
console.log(new Set([...s8].filter(x=>!s7.has(x))));//查找两个Set没重复出现的元素

//WeakSet使用,操作对象
let ws = new WeakSet();//WeakSet成员只能是对象
let o1 = {x:'hello'};
let o2 = [[1,2,3],[4,5,6]];
ws.add(o1);
console.log(ws);
ws.add(o2);
console.log(ws);
console.log(ws.has(o1),ws.has(o2));
ws.delete(o2);
console.log(ws.has(o1),ws.has(o2));
console.log(ws.size,ws.forEach);//WeakSet没有这两个属性,不支持遍历

//Map使用对象来作为键
let m1 = new Map();
let oKey = {x:'hello'};
m1.set(oKey,'Object Value');
console.log(m1);
console.log(m1.get(oKey));
console.log(m1.has(oKey));
m1.delete(oKey);
console.log(m1.has(oKey));

let m2 = new Map();
m2.set(1,'hello');
m2.set(1,'world');
console.log(m2.get(1));//键值相同最后一次值覆盖前一次值
console.log(m2.get(2));//键值不存在,返回undefined

let m3= new Map();
m3.set(['a'],555);//这里的['a']与下面的['a']为两个不同地址
console.log(m3);
console.log(m3.get(['a']));//undefined

let m4= new Map();
let key = ['a'];
m3.set(key,555);
console.log(m3.get(key));//这样可取到值,因为key是同一地址

//下面虽然['a']看起来是相同,实际是不同,分别在不同的地址上
let k1 = ['a'];
let k2 = ['a'];
let m5 = new Map();
m5.set(k1,123);
m5.set(k2,456);
console.log(m5);
console.log(m5.get(k1),m5.get(k2),m5.size);

m5.delete(k2);
console.log(m5);
m5.clear();
console.log(m5);

//Map与对象之间转换,前提 Map的所有键都是字符串
let strMap = new Map();
strMap.set('name','hello');
strMap.set('work','IT');
console.log(strMap);
let obj =Object.create(null);
// @ts-ignore
for (let [i,v] of strMap) {
    console.log(i,v);
    obj[i]=v;
}
console.log(obj);

let newObj = obj;
let newMap = new Map();
for (let i of Object.keys(newObj)) {
    newMap.set(i,newObj[i]);
}
console.log('NewMap:',newMap);

//Map与JSON之间转换 ,前提是所有Map键都是字符串
let jsonstr = JSON.stringify(obj);
console.log(jsonstr);
let jsonObj = JSON.parse(jsonstr);
for (let i of Object.keys(jsonObj)) {
    newMap.set(i,jsonObj[i]);
}
console.log('Json to Map :',newMap);

//WeakMap的键名只能是对象,WeakMap不支持遍历
let wm = new WeakMap();
let objKey = {x:'kkk'};
wm.set(objKey,'ok');
console.log(wm.get(objKey));
console.log(wm.has(objKey));
wm.delete(objKey);
console.log(wm.get(objKey));