- 两个数组的交集和差集
let intersection = a.filter(v => b.includes(v))
let difference = a.concat(b).filter(v => !a.includes(v) || !b.includes(v))
let intersection = a.filter(v => b.includes(v))
let difference = a.concat(b).filter(v => !a.includes(v) || !b.includes(v))