Set
一个存储任意类型的结构,且保证成员是独一无二的。与数组不同的是,不能用下标访问Set
内的成员。
const people = new Set();
API
add()
:类似于数组中的push,添加成员size
:获取长度,而不是用length
people.add('one'); people.add('day'); people.add('oneday'); //Set(3) {"one", "day", "oneday"} people.size; // 3
values()
:将set内的成员变成一个Generator
,可以进行next()
操作const it = people.values(); it.next(); // {value: "one", done: false} it.next(); // {value: "day", done: false} it.next(); // {value: "oneday", done: false} it.next(); // {value: undefined, done: true}
delete()
:删除一个元素people.delete('oneday'); // Set(2) {"one", "day"}
has()
:判断是否含有某个成员people.has('one')); //true people.has('oneday')); //false
keys()
:遍历entries()
:也是遍历for...of
:还是遍历forEach(callback)
:可以添加一个callback函数的遍历people.keys(); // SetIterator {"one", "day"} people.entries(); // SetIterator {"one", "day"} for (person of people) { console.log(person); // one \n day } people.forEach((value) => { console.log(value + 'aaa') // oneaaa \n dayaaa })
clear()
:清空setpeople.clear(); // Set(0) {}