判定偶数
function collect_all_even(collection) { return collection.filter(item => item%2 == 0); }
两个集合的交集
return collection_a.filter(item_a =>
collection_b.some(item_b =>
item_a == item_b
)
);
两个集合的并集
function get_union(collection_a, collection_b) { return new Set([...collection_a,...collection_b]); }
原文:https://www.cnblogs.com/duiniweixiao/p/8998062.html