https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/Set/clear
Set.prototype.clear() - JavaScript | MDN
Set 实例的 clear() 方法移除该集合中的所有元素。
set prototypejavascript mdn
https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Global_Objects/Set/has
Set.prototype.has() - JavaScript | MDN
La méthode has() renvoie un booléen qui indique s'il existe un élément de l'ensemble Set avec une certaine valeur.
set prototypejavascript mdn
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set/union
Set.prototype.union() - JavaScript | MDN
The union() method of Set instances takes a set and returns a new set containing elements which are in either or both of this set and the given set.
set prototypejavascript mdn