二进制权限管理

const READ = 0b00001
const WRITE = 0b00010
const DELETE = 0b00100

const perm = READ | WRITE // 0b00011

perm & READ // 1
perm & DELETE // 0
console.log((perm & READ ) === READ) // true

// 删除权限
const newPerm = perm & ~READ