js 双重for循环优化为.map写法

Question

 let permissionId = []
      for (const i in menuList) {
        for (const j in permission) {
          if (menuList[i].id == permission[j].id) {
            permissionId.push(menuList[i].id)
          }
        }
      }

以上代码如何优化为.map的写法呢

在这里先谢谢各位大神们的解答了，小弟感激不尽！

Answer 1

const map = permission.reduce((r, i) => (r[i.id] = true, r), {})
const permissionId = menuList.filter(i => !!map[i.id]).map(i => i.id)