es6(10)--Set,Map(1)

//Set
{
    let list=new Set();
    list.add(5);//添加
    list.add(7);
    //属性size就是长度
    console.log('size',list.size);//2
}
{
    let arr = [1,2,3,4,5];
    let list = new Set(arr);
    console.log(list.size);//5
}
{
    //去重
    let list = new Set();
    list.add(1);
    list.add(2);
    list.add(1);
    console.log('size',list);//1,2,没有最后的1

    let arr=[1,2,3,1,2];
    let list2=new Set(arr);
    console.log('unique',list2);//1,2,3,没有后面的1,2
}
{
    let arr=['add','delete','clear','has'];
    let list=new Set(arr);
    console.log('has',list.has('add'));//查看是否存在
    console.log('delete',list.delete('add'),list);//删除
    console.log('clear',list.clear('add'),list);//清空
}
//遍历
{
    let arr=['add','delete','clear','has'];
    let list=new Set(arr);

    for(let key of list.keys()){
        console.log('key',key);
    }
    for(let value of list.values()){
        console.log('keys',value);
    }
    for(let [key,value] of list.entries()){
        console.log('entries',key,value);
    }
    list.forEach(function(item){
        console.log(item)
    })
}
//WeakSet:元素只能是对象，不能是数值，不能遍历，没有clear方法，没有set属性
{
    let weakList=new WeakSet();
    let arg={};
    weakList.add(arg);
    //weakList.add(2);不能是数值
    console.log('weakList',weakList);
}
//Map,遍历和set一样
{
    let map= new Map();
    let arr=['123'];
    map.set(arr,456);//添加元素（key,value）
    console.log('map',map,map.get(arr));//get(key)获取值
}
{
    let map= new Map([['a',123],['b',456]])
    console.log(map,map.size)
    console.log(map.delete('a'),map)
    console.log(map.clear(),map)
}
//同WeakSet
{
    let weakmap=new WeakMap();
}