let a=new Map();
let key={name:"ww",sex:"man"};
a.set(key,'ABC');
console.log(a)//{{name:"ww",sex:"man"}=>"ABC"}
let b=new Map();
b.set('name','zhangsan');
console.log(b)//{'name'=>'zhangsan'}
get()方法可以向map對象獲取一個屬性值
let a=new Map();
let key={name:"ww",sex:"man"};
a.set(key,'ABC');
console.log(a.get(key))//'ABC'
has()方法檢測map對象中是否存在某個屬性，返回bool
delete()方法刪除map對象中某個鍵，返回bool
let a=new Map();
let key={name:"ww",sex:"man"};
a.set(key,'ABC');
console.log(a.has(key))//true
a.delete(key);
console.log(a.has(key))//false
?Map()函數接受數組作為參數，最少必須是二維雙數組，長度為2
let a=new Map([['name','wangwei'],['sex','man']]);
console.log(a)//{'name'=>'wangwei','sex'=>'man'}
let b=new Set([['a','A'],['b','B']]);
let c=new Map(b);
console.log(c)//{'a'=>'A','b'=>'B'}
Map()函數接受iterator接口，Map可以自己賦值，注意：不可以對象初始化Map
let b=new Set([['a','A'],['b','B']]);
let c=new Map(b);
let d=new Map(c);
console.log(d)
Map函數初始化，注意：數組引用必須相同才會覆蓋
let a=['a','A'];
let b=['a','A'];
let c=new Map();
c.set(a,1);
c.set(b,2);
console.log(c.get(a),c.get(b))// 1 2 let a=['a','A'];
let b=a;
let c=new Map();
c.set(a,1);
c.set(b,2);
console.log(c.get(a),c.get(b))// 2 2
size屬性獲取map對象成員個數
clear()屬性清除map對象的成員
forEach()遍歷
keys()
entries()
values()
let a=new Map([[1,'a'],[2,'b'],[3,'c']]);
for(let i of a){console.log(i)
}
//[1,'a'],[2,'b'],[3,'c']for(let i of a.keys()){console.log(i)
}//1 2 3for(let i of a.values()){console.log(i)
}//a b cfor(let [key,value] of a.entries()){console.log(key,value)
}//1 'a' 2 'b' 3 'c'
Map轉換為數組 方法 ...|...keys()|...values|...entries
let a=new Map([[1,'a'],[2,'b'],[3,'c']]);
let b=[...a];
console.log(b)//[[1,'a'],[2,'b'],[3,'c']]
let c=[...a.keys()];
console.log(c)//[1,2,3]
let d=[...a.values()];
console.log(d);//["a", "b", "c"]
let e=[...a.entries()];
console.log(e);//[[1,'a'],[2,'b'],[3,'c']]
?Map對象轉換為對象，注意：Map的鍵必須全部是字符串
let a=new Map([['a','A'],['b','B'],['c','C']]);
let b={};
for(let [key,value] of a){b[key]=value
}
console.log(b)//{a: "A", b: "B", c: "C"}
對象轉換為Map
let a=new Map();
let b={a: "A", b: "B", c: "C"};
for(let i in b){a.set(i,b[i])
}
console.log(a)//{"a" => "A", "b" => "B", "c" => "C"}
